Question

21 - r = -87 + 2r Solve

Answer 1

R=36

Explanation:
21-r=-87+2r
+87 +87
108 - r = 2r
+r +r
108 = 3r
/3 /3

Solution: 36=r

Answer 2

Mover terms

-r-2r=-87-21

collect like terms

-3r=-108

Divide


Solution:

R=36