James spends 40 years teaching.  His partner has been teaching for 10 years less.  How long is their combined experience?
His partner has been teaching for 40-10=
<gadget id="calculator">40-10</gadget>
<output>30</output>
30 years.
So together they have 40+30=
<gadget id="calculator">40+30</gadget>
<output>70</output>
70 years of experience.

<result>70</result>