1) First stepis
how they leave the bookstore at the same time , in opposite directions, they are equidistant from the point of reference, that is the bookstore,it means 87/2 = 43,5 miles, now it has been in 3 hours, then for Alexis his speed is
V= X/t , V = 43,5 m/3h = 14,5m/h
Now Julia's speed is 7 m/h faster than alexis , it means 14,5 + 7 = 21,5 m/h
