Answer:
22/3
Step-by-step explanation:

There are 2 ways to do this. I'm going to do it the way that I think is most simple.
You have to find their LCM which is 40. Now times 40 to 1/4 v and 7/10
The equation then becomes 10+40v=28
You simplify it: 40v=18
v= 9/20
the answer to your question for a base area is 100