The answer to this will be 40=15+c and this is because it’s sag 40 is the sum. With that we know that 40 is how they have in total and the word sum indicates that it’s addition. After that it says of 15 and Craig’s saving. We know that it’s addition so we can make it 15+c and then your equation is complete with 40=15+c which also means the Craig had 25 dollars