John has to restring 3 basses with 4 strings each, twice as many guitars which have 6 strings each, and 3 fewer 8 string guitars than the normal guitars.  How many strings does he need?
The basses take 3*4=
<gadget id="calculator">3*4</gadget>
<output>12</output>
12 strings.
He restrings 2*3=
<gadget id="calculator">2*3</gadget>
<output>6</output>
6 normal guitars.
That takes 6*6=
<gadget id="calculator">6*6</gadget>
<output>36</output>
36 strings.
He restrings 6-3=3 guitars with 8 strings.
So that uses 3*8=
<gadget id="calculator">3*8</gadget>
<output>24</output>
24 strings.
So he uses 12+36+24=
<gadget id="calculator">12+36+24</gadget>
<output>72</output>
72 strings.

<result>72</result>