We can set an equation for cost per gallons.
Let $y be cost per gallons:
0.5y = 1.47
y = 1.47 ÷ 0.5
y = 1.47 ÷ 1/2
When division is carried out, the numerator amd denominator will switch, changing division into multiplication:
y = 1.47 × 2
y = 2.94
Therefore, a gallon cost $2.94.
Hope it helps!