For the 1st one it would be 7.8. This is because 7+0=7 and then adding a decimal when it is 0.8 as in your problem you add the 8 to the end not the beginning. The second one is 8.3 because anytime you multiply by 1 you get the same number. For the third problem you add what is in the parentheses because in PEMDAS you always start with parentheses. So, 4+7=11. Next, you will add 11 and 3.5 which is 14.5. I hope this helps!