The washer man irons 4 shirts in 12 minutes. How many shirts he ironed in one hour?

🧠 Explanation (Math):

Given: 4 shirts in 12 minutes; shirts in 1 hour (60 min)?
Step 1: Rate per minute = 4/12 = 1/3 shirt/min
Step 2: In 60 minutes ⇒ 60 × (1/3) = 20 shirts
Final Answer: 20