Their distance differs by 15 miles for each hour of travel time. Thus, the travel time of interest is
.. (180 -144) miles/(15 miles/hour) = 2.4 hour
The red car's speed is 180 mi/(2.4 h) = 75 mi/h.
The blue car's speed is 144 mi/(2.4 h) = 60 mi/h.
https://www.khanacademy.org/math/algebra/one-variable-linear-inequalities/compound-inequalities/v/compound-inequalities
Once you see that it will be the first video that you will click on. Let see if that helps you or if it doesn't help then you can ask your teacher to help you.
1/3x=20
1st step do the opposite of 1/3x to get it by itself. So you would do 1/3x *3/1 than you would do 3/1 *20. What you do to that side you do to the other.
2nd step 20*3=60
3rd You can check your answer by doing 1/3 *60=20
I plugged the answer in the variable to Check it
-4 - (-36) = -4 + 36 = 32 units
