Question 153333
ABC-d-e-f-g-h-i-j=100


Plug in a number for ABC that is somewhere in the hundreds (three digits, of course)  Probably somewhere in the 100's, since you need to end up with 100 subtracting only single digits after the number (if the number is too big, it won't work).  I picked 150 first, because it is just in between 100 and 200:


150-2-3-4-6-7-8-9=100
150-39=100
Nope. Try (significantly) lower.



Maybe 130.
130-2-4-5-6-7-8-9=100
130-41=100
Nope. Too low.


So now you know that it is somewhere between 130 and 150.
Maybe 140, since it is in the middle.


140-2-3-5-6-7-8-9=100
140-40=100
Yep. Just right.


Answer: 140