Algebra Help?!?!!?

Question

Thelmas average driving speed is 6 miles per hour faster than dougs in the same length of time it takes thelma to drive 168 miles doug only drives 150 miles what is thelmas average driving speed?

Answer 1

56 miles per hour for thelma
50 miles per hour for doug


t(s+6)=168
t(s)=150

subtract

t(6)=18
t=3

time is 3 hours

Answer 2

168-150 = 18
18 miles is the extra distance Thelma drives; since Thelma drives 6 miles per hour more than Doug, then we can find the time both Thelma and Doug take to drive the above mileage by dividing the difference of miles with the extra miles per hour that Thelma drives.

18/6 = 3
So, 3 hours is the time taken by Thelma to drive 168 miles, and Doug to drive 150 miles.

So Doug drives 150/3 = 50 miles per hour; since Thelma's speed is 6 miles per hour more, 50+6 = 56 miles per hour. This is also given by 168/3 = 56 miles per hour.

Answer 3

So, let Doug's speed be x.
Therefore, Thelma's is x+6.

168/(x+6) = 150/x

Now, cross multiply. (top left x bottom right = top rightxbottom left)

168(x) = 150(x+6)

Distribute the 150 through the bracket.

168x = 150x + 900

Move the 150x to left by making it the opposite operation.

168x-150x=900
18x=900

Move the 18 over to the right by making it the opposite operation.

x = 900/18
x=50

So, Doug's speed is 50. Thelma's is 56.

Answer 4

(6+x)t=168
xt=150
find x
distribute
6t+xt=168
xt=150
factor out xt
6t=18
t=18/6
t=3
then solve for x
150/3=x
then you're done!
x=Doug's average speed