Question

A set costs half as much as a book.A book costs 600$ more than a pen.If the total cost of the three items is 6900$,find the cost of a set.

Answer 1

B = 2S

B - 600 = P

B + P + S = 6900

2S + (B-600) + S = 6900

2S + (2S-600) +S = 6900

Solve for S.