An integer is all whole numbers and zero, are the numbers you are talking about negatives?
45 minutes.
3 x
--- ----
4 60
you multiply 60 and 3.
you get 180, then you divide by 4 and get 45 minutes.
If you have to estimate I will put $85 and then to find 20 % you just have to kniw that 10% is equal to 8.5 you just move a decimal then you just add 8.5 plus 8.5 = 17 so 20% of 85 is equal to $17 and to find 15% you already know how much is 10%=8.5 so you just need to find 5% that is equal to 4.25 and then you just add 4.25 to 8.5 and that's equal to 12.75
20%= 17
15%=12.5
In order to add fractions you need to change the denominators to make sure they are the same. Then, all you have to do is add the two numerators like normal and keep the denominator the same.
Hope this helps!!!! :D