Because F is a midpoint, that means that FG and EF are congruent to each other. So, since FG = 2, that means that EF also equals 2. Because FH also includes FG, you can take the 2 from the FG, and then take that 2 away from 8. Now you know that GH = 6. All that is left is to add all 3 of the units together (2+2+6=10).
