Let's break this problem down step by step.

Step 1: Calculate how many houses one worker can paint.

A single worker can either paint:

• 2 large houses in 3 hours, or
• 3 small houses in 3 hours.

Step 2: Define the total work.

The contractor needs:

• 20 large houses painted.
• 700 small houses painted.

Step 3: Convert the work into a common measure (like "worker-hours").

For large houses:

• Each worker can paint 2 large houses in 3 hours.
• To paint 20 large houses, you would need $\frac{20}{2} = 10$ workers.

For small houses:

• Each worker can paint 3 small houses in 3 hours.
• To paint 700 small houses, you would need $\frac{700}{3} \approx 233.33$ workers.

Step 4: Combine the number of workers needed.

• For large houses: 10 workers
• For small houses: 234 workers (rounding up from 233.33)

Step 5: Total number of workers.

Total number of workers needed is: $10 + 234 = 244$

So, 244 workers are needed to complete the job in 3 hours.

Would you like more details or have any questions about the process?

Here are 5 related questions:

1. What if each worker could paint 4 small houses in 3 hours instead?
2. How many workers would be needed if the contractor only wanted to paint 500 small houses?
3. What if the workers had 6 hours instead of 3 hours to finish the job?
4. How would the number of workers change if they could only paint 1 large house in 3 hours?
5. How many workers would be needed if 50 large houses needed painting instead?

Tip: Always convert tasks into units that make comparison easy, like "worker-hours" or "work per unit time."