I chose to start backwards by decoding the answer.
It appears that 2 is A and 31 is OF,
so I came up with A LOT OF FAST FOOD
That makes the factorization
1533B5E7 = 7*17B7*1283
Fortunately, the problem only asks for a decode of the answer, not of the factorization, so I don't need to figure out that
15330567 = 7*1707*1283.
It wouldn't be too hard, though, because if B > 0 then the product of the three factors is greater than 15,400,000.