Question

5 books and 7 pens together cost Rs 79 7 books and 5 pens together cost rupees 77 find the cost of a pen

Answer 1

hey friend your answer is
let the cost of book and pen is xand y
5x+7y=79_(1)
7x+5y=77_(2)
multiply7 in equation 1 and 5 in equation 2
35x+49y=553
35x+25y=539
solve equation
24y=14
y=14/24
=7/12
5x+7×7/12=79
5x=79-49/12
x=14.98
cost of 1 pen =14.98 ans