To solve this problem, you will have to first find how many US Dollars are in 1 Euro. Upon looking this up, I see that currently 1 Euro is worth 1.23 US Dollars. Next, you must calculate how many liters are in a gallon. Looking this up shows that 1 liter is equal to 0.264 gallons.
Since 0.264 is not a whole gallon and we are asked to find the price per gallon, we should next calculate how many liters can fit in a gallon. To do this, we will divide 1 by 0.264, which gives us 3.78. This tells us that 3.78 liters will fit into a gallon.
The cost of 1L of gas in euros is 1.50 Euros. Since we need 3.78L to equal 1 gallon, we can calculate the cost of this to be:
3.78 * 1.50 = €5.67
Earlier we determined that 1 euro is worth 1.23 US Dollars. Our final step is to convert our €5.67 per gallon to dollars per gallon. To do this, we simply have to multiply 5.67 by 1.23. This gives us $6.97.
So, our answer is that the cost is $6.97 per gallon.
Hopefully this is correct and makes sense to you. This is how I would approach the question.