Find the missing side length, m.

Answer:
m = 5
Step-by-step explanation:
Remark
This is a proportion question. A proportion is 2 equal ratios. There are 4 parts to a proportion. If 3 are known, the 4th can be found.
Formula
AB/AC = RQ/QS
Givens
AB = m
AC = 2
RQ = 10
QS = 4
Solution
m/2 = 10/4 Multiply both sides by 2
2m/2 = 2*10/4 Combine
m = 20/4
m = 5
Answer m = 5