The answer you want is -10
F(g(x)) means you take the g function and put it into x in the f function. He took the function and put it into the g, which was the incorrect order. He should have had this:
All you do is divide by 10
there are 189 whole dimes
If we dialate a function we are just changing what the graph looks like by a stretch or a compression, the function really doesn't change. If a function before the dilation, then it is a function after the dilation. The opposite is also true.
2400 divided by 10 is 240 and 240 x 3 = 720 so your answer would be 720 calories per day