Data Sufficiency

If x, y and z are positive integers, what is the remainder when 100x + 10y + z is divided by 7?

1. y = 6
2. z = 3

The qa is E

you can think of it as a 3 digit number written as xyz.
now to check the divisibility with 7, we need all the 3 values of x, y and z.
1.) gives y but still no clue abt x or z. hence insuff. eliminate a,d.
2.) gives z but still no clue abt x or y. hence insuff. eliminate b.
even after combining 1, 2 we can't tell the value of x. x can be anything from 1 to 9. and so the remainder will change if the value of x changes...so ans is E.

hope it helps...