Where to get credits on up cards up to 10 lvl +?

To upgrade the card to 9lvl need 2000 * 3 = 6000 credits 10 lvl 4000 * 3 = 12 000 credits 11 lvl 8000 * 3 = 24 000 credits 12 lvl 16,000 * 3 = 48 000 credits 13 lvl 32,000 * 3 = 96 000 credits 1...