Answer:
27 years
Step-by-step explanation:
Let Holly's age be h and Aunt's age be a. We can setup 2 equations and solve.
1. 
2. a - 15 = h
We can plug in equation 2 into equation 1 to solve for aunt's age:

Holly's aunt's age is 27
It would be 7.8Since 7 and 4/5ths is a mixed fraction; you would multiply 7X5= 35, then add 35+4= 39. Then you get 39/5=7.8
Step-by-step explanation:
the base is 5unit and the height is 9unit