peg has $30 to spend at the book store. Her coupon is 15% off but she pays 5% tax. what is the most expensive book she can buy?

Answer 1

.85(1.05)x = 30
x=30/(.85(1.05)) = $33.61

Answer 2

where did you get 1.05 from

Answer 3

100% + 5% salestax = 1 + .05 = 1.05

to increase something by 5% , just multiply it by 1.05