David keeps records of his monthly earnings. last month he worked 120 hours and earned $2700. this month he worked 100 hours and earned $2300. which equation could you use to find f(x), the amount he would earn at this rate if he worked x hours?
f(x)=120x+400
f(x)=400x
f(x)=100x+300
f(x)=20x+300
and tell me why it's the . ^-^"