7+(x+5) would be the answer because sum means addition and it says x and 5. then it says 7 plus that so you put 7. In reality you wouldn't need parenthesis, but if you want it to match the phrase, you can put it in parenthesis.
Here bro this should help
You have to muliply it all togeather to get the exact answer. 4 times 10 equals 40 40 times 3 equals 120 then 120 times 6 equals 720 and thats the right answer
The answer would be the first one.