Initial charge charged by the Singer A = $50 Hourly charge of Singer A = $20 Initial amount charged by Singer B = $100 Hourly rate charged by Singer B = $10 Let us assume the time after which both singers will charge the smae amount of money = x Then 50 + 20x = 100 + 10x 20x -10x = 100 - 50 10x = 50 x = 50/10 = 5 So after 5 hours both Singer A and Singer B will charge the same amount of money. I hope the procedure is clear to you and you can attempt such problems in future without needing any kind of help.