Matt did his homework for 150 minutes. He spent 30% of that time on math and 40% on science. He spent the remaining time on other subjects. How much time did Matt spend on homework in other subjects?
Matt spent on math and science 30% + 40% = 70% of the time.
This means he did homework from these two subjects for 70/100 * 150 minutes = 
<gadget id="calculator">70/100*150</gadget>
<output>105</output>
105 minutes.
So Matt spent 150 minutes - 105 minutes = 
<gadget id="calculator">150-105</gadget>
<output>45</output>
45 minutes doing homework from other subjects.

<result>45</result>