The key words here are <em>less than</em> and <em>3 times</em>. Knee pads are represented by the variable<em> k</em>, and 3 times that price would be 3<em>k</em>. Now, skateboards are $5 less than that price, so the expression that gives the price of a skateboard is 3<em>k</em> - $5.
