Combinatorics › Pigeonhole and extremal problems › Coloured beads and balloons
Chameleon colour changes in September
High school · ●●○○○ 20 pts
On an island there live red, yellow, green and blue chameleons. On a cloudy day, either one red chameleon changes its color to yellow, or one green chameleon changes its color to blue. On a sunny day, either one red chameleon changes its color to green, or one yellow chameleon changes its color to blue. In September there were 18 sunny days and 12 cloudy days. As a result, the number of yellow chameleons increased by 5. By how much did the number of green chameleons increase?