I= e/r for r? they want you to solve each of the formulas for the indicated variable, but i don't know what i'm doing.

Teams of 4 are competing in a 1/4 mile relay race. each runner must run the same exact distance. what is the distance each teammate runs?

Celeste wants to have her hair cut and permed and also go to lunch. she knows she will need $50. the perm cost twice as much as her haircut and she needs $5 for lunch. how much does the perm cost?

Which shows the first equation written in slope-intercept form? 1/2 (2y + 10) = 7x