Question 1028649
b(3) = 2 - 3^3 = 2 - 27 = -25 ==> a(b(3)) = a(-25) = 3*-25 - 7 = -75 - 7 = -82

a(3) = 3*3 - 7 = 9 - 7 = 2 ==> b(a(3)) = b(2) = 2 - 2^3 = 2 - 8 = -6.

==> a(b(3)) - b(a(3)) = -82 - -6 = -76.