Let's calculate the amount of each number because we have to assign digits
0 = 4
1 = 6
2 = 4
3 = 2
4 = 4
5 = 8
6 = 8
7 = 7
8 = 5
9 = 2
Total digits = 50
So, let's calculate which digits have a 20% of the total amount of digits. 20% of 50 is 10, so which digits sum 10.
4 + 6 = 10 (so, white cars can be 01, 12, 14)
8 + 2 = 10 (so, white cars can be 35, 56, 59, 69)