3. mike and chris mowed lawns to earn money to go on a trip at the end of the month. mike earned $20 for each lawn he mowed in his neighborhood. chris earned $15 for each lawn he mowed in his neighborhood. mike and chris mowed the same number of lawns by the end of the month. ms. anderson also gave the boys an extra $50 bonus to them with their trip. (a) write two expressions that could be used to determine the total amount of money the boys earned by the end of the month. (b) what does the variable represent in each expression? (c) mike and chris mowed 10 lawns each by the end of the month. they need $500 for their trip. do they have enough money for their trip? show or explain your work.