The millers budget 1/2 of their income for fixed expenses and 1/8 of their income for savings. what fraction of their income is left?

To figure this out you must find a common denominator which is 8. one denominator is already 8 so you just have to multiply the other one to get 8. To do that just multiply the denominator so it will be 1/8, but when you multiply the denominator of a fraction to get a common denominator you have to multiply the numerator by the same number so the fraction will now be 4/8. Now you just have to add the two. 1/8 + 2/8 = 3/8 

1.17+3.99a. you combine the terms with a to create 3.99 and the 1.17 stays because it has no like terms or a variable