Grace and her brother need $400 to go to band camp. Their parents have agreed to help them earn money by paying them $25 each time they mow the lawn and $10 for each hour they babysit their younger brother. They will have to do a combination of both chores to earn the money. Select the equation that represents the number of lawns they can mow, m, and hours they can babysit, b, to earn $400.
M. 10m+ 25b= 400
P. 10m− 25b= 400
R. 25m+ 10b= 400
S. 25m− 10b= 400