Michelangelo has 28 ceilings to paint. This week, he paints 12 of them. Next week, he will paint 1/4 the number of ceilings he did this week. How many ceilings will be left to paint after next week?
After this week, Michelangelo will have 28-12=
<gadget id="calculator">28-12</gadget>
<output>16</output>
16 more ceilings to paint.
Next week, Michelangelo will paint 12/4=
<gadget id="calculator">12/4</gadget>
<output>3</output>
3 ceilings.
Michelangelo will have 16-3=
<gadget id="calculator">16-3</gadget>
<output>13</output>
13 more ceilings to paint.

<result>13</result>