Bunuel
At Larry's Auto Supply Store, Brand X antifreeze is sold by the gallon and Brand Y motor oil is sold by the quart Excluding sales tax, what is the total cost for 1 gallon of Brand X antifreeze and 1 quart of Brand Y motor oil?
(1) Excluding sales tax, the total cost for 6 gallons of Brand X antifreeze and 10 quarts of Brand Y motor oil is $58. (There is no quantity discount.)
(2) Excluding sales tax, the total cost for 4 gallons of Brand X antifreeze and 12 quarts of Brand Y motor oil is $44. (There is no quantity discount.)
Lets assume 1 gallon of Brand X antifreeze costs=
x and 1 quarts of Brand Y antifreeze costs=
y , Thus we need to find: \(x+y= ?\)
(1)==> \(6x+10y=58\)==>\(3x+5y=29\)......a .......... cannot be reduced any further/no specific info.......... Thus insufficient
(2)==> \(4x+12y=44\)==>\(x+3y=11\).......b ............. cannot be reduced any further/no specific info.......... Thus insufficient
(1)+(2)==> \(a-b\) ==>\(2x+2y=18\)==>\(x+y=9\)........................................................................... Thus Sufficient
Hence I would go for
option C.