(7/2)^(-2) = (2/7)^2
note how I took the reciprocal of the fraction to make the exponent positive. The rule is (a/b)^(-c) = (b/a)^c
Then we square each piece of the fraction 2/7 getting
(2/7)^2 = (2^2)/(7^2) = 4/49
4/49 is approximately equal to 0.08163265306122
