You know the total amount, 32.00, and the cost of each gallon, 1.60, so you can make an equation using x as the amount of gallons bought.
1.60x = 32.00
Now just divide 32.00 by 1.60
x= 32.00/1.60
x= 20
X + y = 85
2x + 4y = 218
x = 85 - y
<span>2(85 - y) + 4y = 218 </span>
<span>170 - 2y + 4y = 218 </span>
<span>170 + 2y = 218 </span>
<span>2y = 48 </span>
<span>y = 24 </span>
<span>x = 61</span>
