Answer:
The discount is 19.5 dollars, so the price of the final bill is 65-19.5= $45.5
b=2A/h-a
Step-by-step explanation:
A=1/2h(a+b)
a+b=A/(1/2h)
a+b=A/(h/2)
a+b=(A/1)(2/h)
a+b=2A/h