How to factor out variables?

Question

Some of my basic algebra has been a little lost on me over the summer. I don't have my book with me, help me figure out this question or at least tell me out to set it up

Two buses leave houston at the same time and travel in opposite directions. One bus averages 55mph the other 45mph. When will they be 400 mi apart?

so far all I can remember is 45x+55y=400 tell me if that right and how can i factor out the y?

Answer 1

Let t = time for the two buses to be 400 miles apart.

Then, the equation is:

55 mph (t) + 45 mph (t) = 400 mi.

Combine like terms. 100 mph (t) = 400 mi.

Isolate t. t = 4 hours.

The two buses will be 400 miles apart after 4 hours.

Answer 2

I'm not sure why you have two different variables in your equation. Let the time that the buses are 400 mi apart be T. Then the first bus has traveled 55T miles and the second bus has traveled 45T miles. This is since (average velocity) = (total distance travelled)/(total time).Thus, 55T + 45T = 400.

You then have the equation 100T = 400.

Divide both sides by 100 to get T = 4 hr.

Answer 3

it would be 45x+55x=400

because they r both traveling miles