Answer:
see below for corrections
Step-by-step explanation:
equation A: 5(1 - 6) + 3r = (21 - 8)
5(-5) + 3r = 13
-25 + 3r = 13
3r = 38
r = 12.667
equation B: 2.7(5.11 + 4.9) = 3.2 + 28.9
2.7(10.01) = 32.1
27.027 = 32.1
no solution (are you missing a variable somewhere?)
equation C: your equation does not make sense. if you fix it, i can help