The answer is 2
See 1 +0 is 1 so 1+1=2
Its 17.5 gallons because 2 quarts times 35 equals 70 quarts and 17.5 gallons equals 70 quarts
You have to make 7 into 21/3. Then change 2 1/3 into 7/3. Then divide 21/3 abd 7/3 which equals 3/3 which equals 1.
From what I learnt so far, there are 3 possible ways of finding whether ratios form a proportion