Just like any other no matter letters or numbers we complete the same process
**LET A BE j, just for equation purposes
[tex]j = \frac{h}{2} (a + b) \\ \frac{j}{(a + b)} = \frac{h}{2} \\ \frac{2j}{(a + b)} = h[/tex]
REMEMBER j is A, so we can rewrite it as
2A/(a+b)=h
**Note: I only used j because I couldn't use capital A in the LaTex system Brainly uses