The gasoline gauge on a van initially read 1/3 full. when 10gallons were added to the tank, the gauge read 3/4 full. how many more gallons are needed to fill the tank?

So it went from 1/3 full to 3/4 full when 10 gallons were put in, so.... what fraction is 10 gallons anyway? let's check the difference.

if say, when full is "x" gallons, 

One shot. if 60% of 10 is 6, then what is 70%? we know it would be seven (since 60% is mathematically 60/100, or 6/10, then 70% is 70/100, or 7/10) but we can check anyway using ratios: 6 : 60% = x : 70%*inverse multiplicationx * 60% = 6 * 70%*divide both sides by 60%x = (6 * 70%) / 60%x = 7and since he has made 6 shots already, he would need just one more to get 7 shots or 70%. if the explanation is too confusing, comment and i will try to