You have to convert the 30 inches into you know what and add them all together
20% of 89.75 is 17.95

so :

the Trina's coupon will subtract the answer by 10%:
10%of 71.8 is 7.18

so the final answer is:

she has to pay $64.62
hope this helps
The answer is 42,84,126 and so on.(you keep on adding 42)
The first question = 3p
The second question =
4x-3y+10z