Robert is building a 15 foot long, 10 foot wide, rectangular wooden fence around his garden.  He needs 2 wood slats for every foot of fencing he builds.  How many wooden slats will he need?
A rectangle has 2 long sides and Robert wants them to be 15 feet long so 2*15 = 
<gadget id="calculator">2*15</gadget>
<output>30</output>
30 feet long.
A rectangle has 2 short sides and Robert wants them to be 10 feet wide so 2*10= 
<gadget id="calculator">2*10</gadget>
<output>20</output>
20 feet wide.
Together, he will need 30 feet and 20 feet of fencing so 30+20 = 
<gadget id="calculator">30+20</gadget>
<output>50</output>
50 feet of fencing.
He needs 2 wooden slats per 1 foot of fencing and he is building 50 feet of fencing so he needs 50*2 = 
<gadget id="calculator">2*50</gadget>
<output>100</output>
100 wooden slats.

<result>100</result>