All x-values less than 21 will work with the known triangle measurements. besides that (x+20)^(∘) must be greater than 0^(∘).
x+20>0 ⇒ x > - 20
Therefore, - 20 is the lower limit of x. We can determine the range of possible values of x by combining the two inequalities. We will rewrite x>- 20 as - 20 < x to make it a bit easier.
Inequality I:&& & x< 21
Inequality II:&& - 20 < & x
Combined:&& - 20 <& x< 21