1200 seconds divided by 3600=
0.33333333 of an hour or a third of an hour.
Or just 20 minutes lol
The vertex is where two lines make a point and the answer would be letter C. A
Before the new kids the ratio of girls to boys is 15:12 because there are 15 girls and 12 boys now you can simplify by dividing 15 by 3 and 12 by 3 to get 5:4 as your simplified ratio. As far as after the new kids. Since there is 1 new girl you do 15+1 to get 16 and there are 3 new boys so you do 12+3 to get 15 now 16:15 is already in simplest form so your answer is:
Before: 15:12 simplified as 5:4
After 16:15
No you have to make sure to line up the decimals when subtracting them. Do not just line of the numbers, this wills get you the wrong answers. Hope this helps. If you need anything else just call for a helping hand.