Christina took $20 with her to the movies. She spent $18, then Meredith gave her $10 that she owed her, and finally she spent $8 more. How much money did she go home with? ( im in 7th grade)

Don't know how to find x given these segment lengths

Two cyclists 84 miles apart start riding toward each other at the same. one cycles 2 times as fast as the other. if they meet 4 hours later, what is the speed (in mi/h) of the faster cyclist?

Which of the following is the best first step in solving the equation below? 4+2㏒³x=17