To answer this question I tried to find a common multiple of 21 and 35 which I found to be 105. As they are in minutes 105 is 1 hour and 45 minutes; after this I found 1 hour 45 munutes after 7:30, I then got 9:15 9:15 is my answer
A differential equation is one that contains the derivative of a function. For example f(x) + 3 = 4f'(x) - 2. Usually you will be given one of the functions and initial conditions if you have to solve.
