Combinatorics › Pigeonhole and extremal problems › Coloured beads and balloons
Blue rectangles on a blackboard
High school · ●●●○○ 50 pts
Blue and red rectangles are drawn on a blackboard. Exactly 7 of the rectangles are squares. There are 3 more red rectangles than blue squares. There are 2 more red squares than blue rectangles. How many blue rectangles are there?