Question

The cost of 5 books and 4 pens is 115. if the cost of 1 book is RS 15 ,find the cost of 7 pens​

Answer 1

The cost of 7 pens is RS 70

Explanation:

Let c=the cost of one book and p=the cost of one pen

5b+4p=115

b=15

5(15)+4p=115

75+4p=115

4p=115-75

4p=40

p=40/4

p=10

7p=7*10

7p=70

The cost of 7 pens is RS 70