Table 2 heheheheheehehehehheheheheehheheheheheheheehehehehhehehehehhehehehehehe
Potential energy = mass * g * height
So here we have:-
54.9 = 8 * 9.8 * h
So
h = 54.9 / (8*9.8) = 0.7 metres
If you would like to calculate A + B and B - A, you can do this using the following steps:
A = 3 * X - 2
B = - 6 * X - 7
A + B = (3 * X - 2) + (- 6 * X - 7) = - 3 * X - 9
B - A = (- 6 * X - 7) - (3 * X - 2) = - 9 * X - 5
The correct result would be B.