Answer,
R = 1
Explanation,
Subtract 10 from both sides,
-3r + 10 - 10 = 15r - 8 - 10
Simplify,
-3r = 15r - 18
Subtract 15r from both sides,
-3r - 10 = 15r - 18 - 15r
Simplify,
-18r = -18
Divide both sides by -18,
-18r/-18 = -18/-18
Simplify,
R = 1
Hope this helps :-)