Here is my friendly solution i'll skip the proof part for now. I am working on the others.
You would need to multiply the monthly cost, $14, by the number of months and then that would be added to the cost to join, $25
For 6 months it would cost 14 x 6 = 84 + 25 = $109
The answer would be C.
Just use your right angled triangle formula.
A=

Plug n chug
A=

A=71.5
Answer:
If Mary earns 7$ an hour, we need to multiplicate 7$ by the number of hours worked for the entire week so we can get the salary per week.
Step-by-step explanation:
it's correct