Algebra
posted by Sylvie .
You and your friend live 12 miles apart. You leave home at the same time and travel toward each other. You walk at a rate of 4 mph and your friend bicycles at a rate of 11 mph. A) How long after you leave home will you meet? How far from home will each of you be? B) Suppose your friend bikes at a rate of 12 mph. How much sooner will you meet? How far from home will each of you be?

let d be the distance you travel. So 12d is the distance friend travels. You both pedal for time t (hrs)
d=4t
12d=11t
add the equations. 12=15t t=12/15 hr
then find d, and 12d from either equation. 
speed toward each other = 11+4 = 15 mph
so time = 12/15 = 4/5 hour = 48 minutes
4/5 * 4 = 16/5 = 3.2 miles
4/5* 11 = 44/5 = 8.8 miles
Now you should be able to do it with a different speed.