0.5 gallons plus 0.5 gallons plus 2 gallons plus 1gallon basicly i need to know how to add gallons.

5 gallons

Step-by-step explanation: the gallons are in decimal points. 1/2 + 1/2 + 2 + 1 = 5. the .05 and 1/2 are the same thing. the .5 + .5 equals 1

if you was gonna solve for a, a is a   < -12

what is the question? i am guessing you are looking for the area.

to find an area, you have to do length x width.

in this case, it would be 12 ft x 4 ft = 48 sq. ft