2
20- buy 15 books
15- buy 20 books
Original price is 20.
A = B + 2
B = 2 C
A + B + C = 27
C = 27 – A – B
B = 2*27 – 2A – 2B
2A = 2*27 – 3B
-2*A =-2*2 – 2*B
B = 10
6 pairs of earrings. So 12 earrings.
The total has to be 26, so let’s say there’s 6 pairs of earrings and the number of pairs has to be 4 less than the number of rings. So that would make 10 rings. The 10 rings has to be 2 1/2 greater than the number of pins. So you would divide 10/2.5 = 4 Pins. That would equate to a total of 12 earrings, 10 rings, and 4 pins. A total of 26 pieces.
Days taken by A to complete whole work= 140 days
Days taken by B to complete whole work= 105 days
A’s 1 day work= 1/140
B’s 1 day work= 1/105
On adding these together we get: 1/60 (1 day work by working together)
So, together they will be able to complete it in 60 days
In the example first we have to find the area of the field
we have given the following values ,
cost of fencing per meter = Rs 1.50
Diameter of circular field = 28
We have to find the area , a = ?
We know that,
Area = 2 π r
= 2 x 22/7 x 14
= 2 x 22 x 2
= 44 x 2
= 88 sq. m
So, area of circle is 88 sq.m
Now just multiply it with 1.50
cost of fencing = 88 x 1.50
= Rs. 132
So, the cost of fencing the circular field is Rs. 132
A. 978626
120 (5×4!)
% error= (new no-actual no)/actual no *100
% error= [(x/7)-7x]/7x * 100
% error= 48x/49x * 100
% error= 0.9795*100=97.95
south east
A. Rs. 8000, Rs. 7500, Rs. 3500
125, 123, 120, 115, 108, 100, 84
b
Hint: Assume that the speed of the stream is x and the speed of the boat in still water is x. From the statement of the question form two equations in two variables x and y. This system is reducible to linear equations in two variables. Reduce the system to a system of linear equations in two variables by proper substitutions. Solve the system of equations using any one of the methods like Substitution method, elimination method, graphical method or using matrices. Hence find the value of x satisfying both the equation. The value of x will be the speed of the stream.
Complete step-by-step answer:
Let the speed of the stream be x, and the speed of the boat in still water be y.
We have the speed of the boat upstream = y-x.
Speed of the boat downstream = y+ x.
Now since it takes 14 hours to reach a place at a distance of 48 km and come back, we have the sum of the times taken to reach the place downstream and time taken to return back upstream is equal to 14.
Now, we know that time =Distance speed
Using, we get
Time taken to reach the place =48y+x and the time taken to return back =48y−x.
Hence, we have
48y+x+48y−x=14
Dividing both sides by 2, we get
24y+x+24y−x=7 —–(i)
Also, the time taken to cover 4km downstream is equal to the time taken to cover 3km upstream.
Hence, we have 4y+x=3y−x
Transposing the term on RHS to LHS, we get
4y+x−3y−x=0 ——– (ii)
Put 1y+x=t and 1y−x=u, we have
24t+24u=7 ——-(iii)4t−3u=0 ——–(iv)
Multiplying equation (iv) by 6 and subtracting from equation (iii), we get
24t−24t+24u+18u=7⇒42u=7
Dividing both sides by 42, we get
u=742=16
Substituting the value of u in equation (iv), we get
4t−3(16)=0⇒4t−12=0
Adding 12 on both sides, we get
4t=12
Dividing both sides by 4, we get
t=18
Reverting to original variables, we have
1y+x=18 and 1y−x=16
Taking reciprocals on both sides in both equations, we have
y+ x=8 ——- (v)y−x=6 ——–(vi)
Adding equation (v) and equation (vi), we get
2y=14
Dividing both sides by 2, we get
y=7.
Substituting the value of y in equation (v), we get
7+x=8
Subtracting 7 from both sides we get
x = 8-7 =1
Hence the speed of the stream is 1 km/hr.
9