To solve for \( r \) in the equation \( 17r - 13r = 20 \), we first combine the terms on the left side:
\[ (17r - 13r) = 4r \]
So the equation simplifies to:
\[ 4r = 20 \]
Next, we divide both sides by 4 to isolate \( r \):
\[ r = \frac{20}{4} = 5 \]
Thus, the solution is:
\[ r = 5 \]