Question 30760
this question can be directly solved by applying the formula...

area of circle = ∩(pie) r^2

                 =  22/7 * (7)^2

                 = 22/ 7 * 49

                 = 22 * 7 

                 = 154 square inches

but I think your question demands to apply direct variation method here ...so if we find it by direct variation then we get equation...

(5)^2 /78.5 =(7)^2 / x    [x here is area of circle which u wish to find out]

on solving it we get x = 153.86 or 154 (appoximately)

Still if you won't be able to solve further, contact me again. 

hope this will help you 

Please feel free to revert back for any further queries.