Dave can wash $2$2 cars in $4$4 minutes.

How long would it take for him to wash 1 car?

How long would it take him to wash $20$20 cars?

Neil can walk $7$7 dogs in $49$49 minutes.

Buzz bought $6$6 stamps for $24.

Neil bought $10$10 stamps for $50.

Reason with linear proportions.