Answer:
The ratio of boys to girls is 4:5. So let 4x be the number of boys and 5x be the number of girls. Then 4x+5x = 9x is the total number of students. Then the fraction of boys in the class is 4x/9x = 4/9.
Theres about 800 different combinations, i'm not sure though, i'm sorry if i'm wrong
So,
The rate of the train is 25mi/20mins. We need (x)mi/hr. We can do that by multiplying by 3.
25(3) = 75
The train's speed in mph is 75 mph.
So the answer is 1sundae :$4 2 milkshakes:$6 total:$10
$23.58 divided by 12 = $1.965
Each roll is about $1.97 (if you round up)