Madeline and her roommate, Keenan, share the cost of groceries. In total, they spend about $400 per month. In a four-week month, how many dollars does Keenan spend per week if Madeline pays 60% of the cost?
They spend $400/4=$
<gadget id="calculator">400/4</gadget>
<output>100</output>
100 per week.
Keenan pays for 100-60=
<gadget id="calculator">100-60</gadget>
<output>40</output>
40% of the groceries.
Thus, she spends $100*(40/100)=$
<gadget id="calculator">100*40/100</gadget>
<output>40</output>
40 per week.

<result>40</result>