Bobby can deadlift 300 pounds at 13.  When he is 18 he can deadlift 100 pounds more than 250% of his previous deadlift.  How many pounds did he add per year?
His new deadlift is 300*2.5+100=
<gadget id="calculator">300*2.5+100</gadget>
<output>850</output>
850 pounds.
So he added 850-300=
<gadget id="calculator">850-300</gadget>
<output>550</output>
550 pounds to his deadlift.
This took 18-13=
<gadget id="calculator">18-13</gadget>
<output>5</output>
5 years.
So he added 550/5=
<gadget id="calculator">550/5</gadget>
<output>110</output>
110 pounds per year.

<result>110</result>