Trent caught 180 tadpoles then let 75% of them go. How many did he keep?
First find the number of tadpoles Trent released: 180 tadpoles * .75 = 
<gadget id="calculator">180*.75</gadget>
<output>135</output>
135 tadpoles.
Then subtract the number he let go from the total number to find the number of tadpoles he keeps: 180 tadpoles - 135 tadpoles = 
<gadget id="calculator">180-135</gadget>
<output>45</output>
45 tadpoles.

<result>45</result>