Answer:
[tex]g=\frac{2\,H}{m+r}[/tex]
Step-by-step explanation:
Starting with :
m g + r g = 2 H
extract "g" as a common factor on the left of the equal sign:
g (m + r) = 2 H
Now, in order to solve for "g" , divide both sides of the equal sign by the binomial (m + r):
g = (2 H )/(m + r)
[tex]g=\frac{2\,H}{m+r}[/tex]