To solve this problem, we can use the following equation to find the forward force (F):
F = 280 N * cos(40.0°)
Plugging in the values, we find that:
F = 280 N * cos(40.0°)
= 280 N * 0.766
= 215.28 N
Therefore, the force pushing the lawn mower forward is 215.28 N.