The answer would be m^2+3m+2=0 because the first “part” of the equation (x^2-5) is equal to m; in the equation it’s squared so it can be replaced by m^2. next, 3m is the same as 3(x^2+5) which is what you have when you see 3x^2+15. finally, you have to bring the -2 over from the other side so you have positive 2. hope this helps!
X + (x + 1) + (x + 2) = 126
3x = 123
x = 41
So the sides are 41, 42 and 43
