Answer
$ 6$
Work Step by Step
The problem states triangle FGH is similar to triangle MNP. So side NP is proportionate to side GH. NP is 10 and GH is 20. Sp NP/GH is 1/2 and triangle MNP/triangle FGH have a ratio of 1/2. To find x, which is the length of NM, we need to use side GF, which is 12 units. NM/GF must be 1/2, so x/12 =1/2. Thus, x equals 6.