so basically .... here is how we need to solve these :
we need to take each digit from the left one by one ... multiply it with 4 and subtract that with 9
so .... first.. the number 0
(0) × 4 - 9 = 0 - 9, ∴ = -9
2. (1) × 4 - 9 = 4 - 9 , ∴= -5 ( as we go on subtracting 4 from 9 is becomes negative or in other way .... if the smaller number is first then the answer will be negative )
3. (2) × 4 - 9 = 8 - 9 , ∴ = -1 ( answer is negative as smaller number is first )
4. (3) × 4 - 9 = 12 - 9 , ∴ = 3
5. (4) × 4 - 9 = 16 - 9 , ∴ = 7