Sale tax rate: 4%
Sale tax price : $6
Purchase price (x) multiplied by the tax rate in decimal form (divided by 100) must be equal to the sale tax amount:
x (4/100) = 6
Solve for x:
0.04x = 6
x = 6/0.04
x= $150
Purchase price: $150
Total price= purchase price + sale tax amount= 150+6 = $156