Tonya spent $90.00 on art supplies.  4 canvases cost $40.00 and a mixed set of paints cost 1/2 that much. She also spent $15.00 on an easel, and the rest of the money on paintbrushes. How much money did she spend on paintbrushes?
The canvases cost $40.00 and she spent half that amount on paint so she spent 40/2 = $
<gadget id="calculator">40/2</gadget>
<output>20</output>
20.00 on paint.
She spent $40.00 on canvases, $20.00 on paint and $15.00 on an easel so she spent 40+20+15 = $
<gadget id="calculator">40+20+15</gadget>
<output>75</output>
75.00.
She spent $90.00 total and her other purchases totaled $75.00 so she spent 90-75 = $
<gadget id="calculator">90-75</gadget>
<output>15</output>
15.00 on paint brushes.

<result>15</result>