Answer:
5.83333333
Step-by-step explanation:
6x + 16 = 51 (If that is what you actually intended to put)
6x + 16 - 16 = 51 -16
6x/6 = 35/6
x=5.83333333
a=-3
5a+a=-10-8
6a=-18
a=-18/6
