I think on 5, y is 20 and x is 100. On number 6, y would be 8 and x would be 5.
(-1) ^ 101 is -1
to an even power it would be 1
negative* ( negative ) = positive
to an odd power it is negative
positive * negative = negative
since 101 means there are (-1) *-1.......101 time
it is odd
-1 *-1 =1
this is an even power
1 * -1 = -1
this is an odd power
since 101 is odd
it will be negative
Just use the known formula...
pi * r^2