How do you solve #(x + 5)(3x+1)=0#?
You can easily solve this equation by recognizing that the product of two terms is equal to zero if either one of those terms (or both, that's not the case here) is equal to zero.
In your case, the product of
#(x+5) = 0#or #(3x+1) = 0#
This means tha the two solutions to your equation will be
If, for some reason, you'd want to complicate things a little, you could rewrite your equation in quadratic form
and use the quadratic formula to solve for the two solutions.
#color(blue)(x_(1,2) = (_b +- sqrt(b^2 - 4ac))/(2a)#
In your case, you have
Once again, you'd get