To order the steps for proving that the sum \( t = r + s \) is irrational if \( r \) is rational and \( s \) is rational, you would arrange the steps as follows:
- Step 2. For a contradiction, assume that \( t \) is rational, and write \( r \) and \( t \) as fractions.
- Step 1. Subtract, writing \( s \) as a fraction.
- Step 4. Find a common denominator.
- Step 3. Realize a contradiction.
This order follows the logical flow of assuming \( t \) is rational, expressing the relevant quantities as fractions, manipulating them to find a common basis for comparison, and ultimately arriving at a contradiction that shows \( t \) cannot be rational.