The total money spent for the Dinner and Dessert is $22 so to figure out how much was spent on the taxi ride you're going to want to subtract $22 from $31 (31 = x + 22) or (31 - 22 = x).
It wouldn't be able to be because since all of the the numbers that could fit is probably going to be a decimal. Let's say we find 4 consecutive numbers of 32.
Equation:
x+(x+1)+(x+2)+(x+3)=32
4x+6=32
-6 -6
4x=26
x=6.5 1. 6.5, 7.5, 8.5, 9.5
As you can see, the consecutive number is going to be a decimal.