You start a lawn care company with four friends. you agree to split the profits equally. the tools you need to buy cost $525. how much income will you have to earn to each make a profit of $400?

Since four friends should make a profit of $400 each, the total undivided profit should be $1600. Profit (P) is the difference between the total revenue (R) and the total cost (C). 
                                   P = R - C      ;    R = P + C 
Substituting the known values, 
                               R = $1600 + $525 = $2125

Thus, the total income that the friends should earn is $2125.