The expression $x^2 + 13x + 30$ can be written as $(x + a)(x + b),$ and the expression $x^2 + 5x - 50$ written as $(x + b)(x - c)$, where $a$, $b$, and $c$ are integers. What is the value of $a + b + c$?
Try to factor by grouping.
x2+13x+30=(x2+10x)+(3x+30)=x(x+10)+3(x+10)=(x+3)(x+10)
x2+5x−50=x2+10x−(5x+50)=x(x+10)−5(x+10)=(x−5)(x+10)
The rest is trivial.
Hints: Find b first.
+335 
