I got 5x+8 but I don’t know what to do after this, please help!

The sum of the speeds of two trains is 720.2 mph. if the speed of the first train is 7.8 mph faster than the second train, find the speeds of each.

G. how many different 6-letter arrangements can be formed using the letters in the word absent, if each letter is used only once? a. 6 b. 36 c. 720 d. 46,656

On ryan's last social studies test there were two types of questions true/false worth 3 points each and multiple choice questions worth 4 points each