Jill bought 5 packs of red bouncy balls and 4 packs of yellow bouncy balls. Each package contained 18 bouncy balls. How many more red bouncy balls than yellow bouncy balls did Jill buy?
Jill bought 5 packs * 18 red balls = 
<gadget id="calculator">5*18</gadget>
<output>90</output>
90 red balls.
Jill bought 4 packs * 18 yellow balls = 
<gadget id="calculator">4*18</gadget>
<output>72</output>
72 red balls.
Jill had 90 red - 72 yellow = 
<gadget id="calculator">90-72</gadget>
<output>18</output>
18 more red balls.

<result>18</result>