The answer is (change of amount) / (change of time). For the change of amount, the numerator is 40 seagulls - 16 seagulls, leaving a total of 24 seagulls. For the change of time, the denominator is 3 pm - 1 pm, leaving a total of a 2 hour difference. The answer becomes 24 seagulls / 2 hours, or 12 seagulls per hour when simplified.
