Answer :
p = 2m + 2u
Goal: Isolate "m"
p - 2u = 2m + 2u - 2u
p - 2u = 2m
(p - 2u)/2 = (2m)/2
p/2 - u = m
m = p/2 - u
Goal: Isolate "m"
p - 2u = 2m + 2u - 2u
p - 2u = 2m
(p - 2u)/2 = (2m)/2
p/2 - u = m
m = p/2 - u