The polynomial remainder theorem says that the remainder when dividing a polynomial \(P(x)\) by a linear divisor \(x-k\) is simply \(P(k)\).
If \(P(x)=5x^3+49x^2+74x+6\), then the remainder upon dividing by \(x+8\) is
\(P(-8)=-10\)
You could also verify this by actually computing the quotient and remainder.