60 kg of salt water with a salt content of 30% is evaporated on a scale. When the salt water becomes 40% salt water, what is the weight of the salt water in kilograms?
含盐30%的盐水有60千克，放在秤上蒸发，当盐水变为含盐40%时，秤得盐水的重是多少千克．
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(3/10) / (2/5)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">60 * (3/4)</gadget>
<output>45</output>

<result>45</result>