Area of a Circle= (pi)(radius) squared
Find the area of each cake, then subtract the difference between those 2 answers to find the difference in area. Also remember the problem gives you diameter, but the area formula requires radius so you must divide the diameter by 2.
Vanilla Cake Area
A= (3.14)(8/2) squared
A=(3.14)(4) squared
A=(3.14)(4*4)
A=(3.14)(16)
A=50.24 inches
Chocolate Cake Area
A=(3.14)(10/2) squared
A=(3.14)(5) squared
A=(3.14)(5*5)
A=(3.14)(25)
A=78.5 inches
Difference in Area
Chocolate Area - Vanilla Area
= 78.5 - 50.24
= 28.26 inches difference
Hope this helped!! :)