original Juice price: $3.50
New price: $3.20
1.
Multiply the original price by the percentage in decimal form ( x) . That expression must be equal to the new price:
3.50 x = 3.20
Solve for x
x = 3.20/3.50
x= 0.91
Multiply by 100
0.91 x 100 = 91%
2.
Cost per gallon $2.70
MArkup if they sell each gallon at $3.20
3.20-2.70 = $0.5
Markup if they sell each gallon at $3.50:
3.50-2.70 = $0.8