3. amar and sang mowed lawns to earn money to go on a trip at the end of the month. they both mowed the same number of lawns. amar earned $20 for each lawn he mowed in his neighborhood. sang earned $15 for each lawn he mowed in his neighborhood. (a) using a variable, write an expression that describes the total amount of money earned by both boys at the end of the month. define what the variable represents. (b) amar and sang mowed 10 lawns each by the end of the month. they need $400 for a summer trip. do they have enough money for their trip? show or explain your work. 99 points