There are 28 students in a class. Two-sevenths of them were absent last Monday. How many students were present last Monday?
28 x 2/7 = 
<gadget id="calculator">28*2/7</gadget>
<output>8</output>
8 students were absent last Monday.
So, 28 - 8 = 
<gadget id="calculator">28-8</gadget>
<output>20</output>
20 students were present last Monday.

<result>20</result>