3n + 7 in word form please help me

Aiden drives to school and back each day. the school is 16 miles from his home. he averages 40 miles per hour on his way to school. if his trip takes 1 hour, at approximately what speed does aiden drive home?

Adj has a total of 1075 dance and rock songs on her system. the dance selection is 4 times the size of the rock selection. write a system of equations to represent the situation.

Determine the required value of the missing probability to make the distribution a discrete probability distribution. x p(x) 3 0.23 4 ? 5 0.51 6 0.08 p(4) = nothing  (type an integer or a decimal.)