The greatest common factor is 6. Thus means we divide every part of the expression by 6.
6x^2/6 = x^2
42x/6 = 7x
-18/6 = -3
Your new expression is 6(x^2 + 7x -3).
The answer is 244 because you add 35 to 287 then subtract 78 and it equals 244
The height of the tower roughly equals 41.421 meters.