20% of 89.75 is 17.95
[tex] \frac{20}{100} = \frac{x}{89.75} \\ x = \frac{89.75 \times 20}{100} = \frac{1795}{100} = 17.95[/tex]
so :
[tex]89.75 - 19.95 = 71.8[/tex]
the Trina's coupon will subtract the answer by 10%:
10%of 71.8 is 7.18
[tex] \frac{10}{100} = \frac{x}{71.8} \\ x = \frac{71.8 \times 10}{100} = \frac{718}{100} = 7.18[/tex]
so the final answer is:
[tex]71.8 - 7.18 = 64.62[/tex]
she has to pay $64.62
hope this helps
