Solve a= (a + b + c + d)/4 for c
Cross multiply:
4a = a + b + c + d
Subtract a + b+ d from each side to isolate c:
4a - a - b - d = a + b + c + d - a - b - d
Canceling the a, b, and d from the right side, we get:
c = 3a - b - d
Cross multiply:
4a = a + b + c + d
Subtract a + b+ d from each side to isolate c:
4a - a - b - d = a + b + c + d - a - b - d
Canceling the a, b, and d from the right side, we get:
c = 3a - b - d