An equation for the sentence would be g + 7 = 12, where g is the unknown number of gallons.
They are all averages
mean=average 4+6=10, 10 divded by 2= 5, the mean is 5
median= middle number, 5 6 7, 6 is the median
mode= most repeated number, so 4,4,4,4,4,4,4,5.5,6 4 is the mode
The distance is 3, because 7 - 4 = 3.
