Sam makes $400 per week plus $20 commission on each new cell phone plan she sells. Write an equation and solve it to determine how many new plans she sold to earn $680 last week.
the equation would be 400+20c per week so if you do that equation, to figure it out 680-400=280 and then you would divide it by 20 and whatever that answer is, in this case it would be 14.
