let 'x' represent the number of weeks that Jason needs to work to save
375 + 155x >= 900
x >= 3.4
if Jason works 3 weeks he will have saves: 375 + 3*155 = $840 which is not enough
thus Jason needs to work at least 4 weeks (by working 4 weeks he will save: 375 + 4*155 = $995).