Hey :) Number 7: -->Let's find the least common multiple of 4, 10, and 12 by listing again: 4: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40... 60 10: 10, 20, 30, 40, 50, 60 12: 12, 24, 36, 48, 60 -->As you can see, the LCM is d or 60 * Just a random thought but did you accidently write 7 for the other one?
Number 8: -->By factoring the expression, you would be finding a factor that both numbers share (usually the GCF) and divide the whole expression by that number: "What is the GCF of 54 and 24?" "6!" --> So now that you know the GCF or just factor, you can divide the expression by it: 54a+24b 54a(/6)+24b(/6) 9a+4b --> Sorry if this gets confusing but now you put the end result in parentheses with what you divided it by on the outside 6(9a+4b) -->Or in other words, answer choice 'c'!
Number 9: -->Sorry but I can't answer it yet because you didn't say what his recipt is. I can help you once you tell me what's on the receipt :)