Question

make the letter in brackets the subject of the formulae:
P=Q+3r/T (r)

Answer 1

P=Q+3r/T
P - Q = 3r/T
PT - QT = 3r
r = (PT - QT)/3

Answer 2

P=Q+3r/T
P-Q=3r/T
T(P-Q)=(3r/T)T
PT-QT=3r
r=(PT-QT)/3