A number when divisible by 45 leaves reminder 30. If the number is divisible by, 5 the remainder must be:

Let the number is x.

Then,              (where, k is 1, 2, 3, 4...)

$\therefore$ Number $\to 45\times 1+30=x$

$75=x$

When, 75 is divisible by 5

Then, remainder is zero.