Question

I thought of a number, multiplied it by 2 1/2, divided the result by 1 1/5, subtracted 7/18 from it, and got 1 5/6. What was my number?

Answer 1

1 and 1/15

Work backwards, so add 7/18 to 1 5/6 first (I'm gonna add them in improper fraction form to make it easier) and you get 40/18 which is 20/9
Then multiply by 1 1/5 (or 6/5) to get 120/45 which simplifies to 8/3
Then divide by 2 1/2, or 5/2, which means you multiply by the reciprocal (2/5)
8/3 times 2/5 equals 16/15 or 1 1/15