Answer:
all work is shown and pictured
(2/3) / 3 = 1/x...2/3 to 3 lawns = 1 to x lawns
cross multiply
(2/3)(x) = (3)(1)
2/3x = 3
x = 3 * 3/2
x = 9/2 or 4 1/2 lawns can be cut with a full tank of gas
50% because you first subtract the original price from the new price so 126-84 equals 42 then you divide that by the original price 84 which will give you .5 which turns to 50%