From the number 9876543210, cross out the smallest number of digits so that the digit in the tens place is three times smaller than the digit in the thousands place, and the digit in the units place is three less than the digit in the hundreds place. Find all solutions.

(S. Bodláková)
The first option is that there will be a 3 in the thousands place and a 1 in the tens place, but then the second condition would not be met.

Therefore, there must be a 6 in the thousands place and a 2 in the tens place. This is possible in two ways while satisfying the second condition. The results will be the numbers 9876320 and 9876421.