Need full answer if you joke around i will report you explain

Following PEMDAS, first you multiply:

Next, you could either multiply all by -3/7 or add 3 to both sides. I will show my work both ways; 

Way 1:

Now multiply both sides by -3/7:


Way 2:

Now subtract 9/7 from both sides:


Both ways work, just depends on which way's more convenient or easiest :)
Your answer is A, 21.

The answer is 326.78.