Three pens and a book cost ₵ 1,200 and two pens and a book also cost ₵ 1,000. Find the cost of 15 pens and 12 books.

Question

Three pens and a book cost ₵ 1,200 and two pens and a book also cost ₵ 1,000. Find the cost of 15 pens and 12 books.

 

I NEED A BRIEF EXPLANATION FOR THIS TYPE OF QUESTIONS.Thank you

Answer 1

Let P be the number of pens and B be the number of books. From the first sentence you can set up the system of equations:

 

3P + B = 1200

2P + B = 1000

 

You want to find what 15P + 12B equals.

 

Using elimination, you can solve for P by subtracting the two equations and then solve for B. Once you know P and B, you can find 15P + 12B.