20 16: 20 (1-6%)+X car ownership.
20 17:[20( 1-6%)+X]( 1-6%)+X = 20( 1-6%)? +( 1-6%)x+x
20 18:20( 1-6%)? +( 1-6%)? x+( 1-6%)x+x
……
20( 1-6%)^n+[ 1-( 1-6%)^n]x/6% & lt; 40
When n tends to infinity, (1-6%) n tends to 0.
Therefore, x