Notice that the bounds have flipped and the integrand is now negative.
Split this problem into a sum of two integrals:
Integral 1: Notice that the bounds shifted 8 units to the right... but so did the integrand: f(x − 8).
Integral 2: This integral represents a rectangular area with base: 12 − 10 = 2 and height: 4.
The bounds shifted 8 units to the right, but the integrand shifted 8 units to the left.
We do not have enough information to evaluate this integral.