Emily is entering a bicycle race for charity. Her mother pledges $0.40 for every 0.25 mile she bikes. If Emily bikes 15 miles, how much will her mother donate?
Set it into proportions.
$0.40/0.25 miles = x/15 miles
And then solve the proportion.
0.25*x = 0.40*15
0.25x = 6
0.25x/0.25 = 6/0.25
x=24
Therefore, Emily's mother donates $24 if she bikes 15 miles.