notice, the factor or divisor is x-5, so we could just do a quick synthetic division on it for x - 5 = 0, x = 5, so, let's divide it by 5.
[tex]\bf \cfrac{3x^2+5x+50}{x-5}\implies
\begin{array}{llllll}
5&&3&5&50\\
&&&15&70\\
--&&--&--&--\\
&&3&20&\boxed{120}\impliedby remainder
\end{array}[/tex]
now, notice the remainder, is NOT 0.