Cost of 5 pens and 7 Notebooks is rs.82 and cost of 4 pen and 4 notebooks is 52. Then the cost of 2 notebook and 3 pens is ??
Answers
30.5 rs
5x+7y=82......
4x+4y=52
20x+28y=328
(-) (-) (-)
20x+20y=260
therefore y=8.5 and x=4.5
Given,
The price of 5pens and 7 books = 82rs.
The price of 4pens and 4 books = 52rs.
To Find,
The price for 2books and 3 pens.
Solution,
Let's assume
cots for 1 pen = p
cost for 1book =b.
The money for 5pens and 7 books
5p + 7b = 82rs ⇒ (1)
The money for 4pens and 4 books
4p + 4b = 52rs ⇒ (2)
To find the value of p and b
multiply (1) with 4 and (2) with 5
20p + 28b =328 ⇒(3)
20p + 20b = 260 ⇒(4)
Let's substract eq (3) and (4)
20p +28b = 328 -
( 20p + 20b = 260)
20p + 28b = 328
20p - 20b = -260
Cancel p terms
8b = 68
b = 68 / 8
b = 8.5rs
Substitute value of b in any equation.
20p + 28 * 8.5 = 328
20p= 328 - 238
p = 90/20
p = 4.5rs.
So, one pen price = 4.5rs
One notebook price = 8.5rs.
the price for 2 notebooks = 2 * 8.5
17
The price for 3pen = 3*4.5
13.5
Hence, the cost for 3pens and 2books is 13.5 and 17.