This is for a maths challenge thing I'm doing but I'm gonna change the numbers around a bit so that I'm not relying on others for help entirely.Please be really clear on the method and steps used-I know you guys are of great help but sometimes your understanding of maths just goes beyond my capabilties.

1. Person A needs a $30. ATMs dispenses either $30, $40 or $70 notes. What is the largest amount he can withdraw to be certain that he has at least one $30 note?

2. A certain positive integer X greater than 100 is displayed. But when its two rightmost digits are erased, the number left is X/154. Find all possible numbers of X.