First recognize that the unit rate we're finding is gallons per hour, or

.
rate for Tank 1 = x gallons per hour = <em>a</em> gallons / <em>b</em> hours

rate for Tank 2 = y gallons per hour = <em>c</em> gallons / <em>d</em> hours
Answer:
If you are solving the equation for x :
3x + 3y = 180
3x = -3y + 180
x = -y + 60 or x = 60 - y
If you are solving the equation for y:
3x + 3y = 180
3y = -3x + 180
y = -x + 60 or y = 60 - x
The prime factorization of 36 would be B. 2 x 2 x 3 x 3