A voice coach charges 165$ for 1.5 hour of work which proportion can be used to find x, the number of dollars the voice coach charges for 4 hours of work
X/4=1.5/165
X/165=3.5/2.5
X/165=1.5/4
X/4=165/1.5
X = 4 * 165 / 1.5
X = 440
Therefore, the voice coach charges $440 for 4 hours of work.