Chapter 6 - Algebra: Equations and Inequalities - 6.3 Applications of Linear Equations - Exercise Set 6.3 - Page 375: 34

$1300$ dollars worth of merchandise and we would spend $1210$ dollars in total.

Let $x$ be the original amount we should have spent on merchandise. Then our equation is: $300+0.7x=40+0.9x\\260=0.2x\\x=1300$ So we would have to buy $1300$ dollars worth of merchandise and we would spend $1210$ dollars in total.