There are 50kg of sugar water, and the ratio of sugar to water is 3:7. How many kilograms of sugar are in the sugar water? (Do it in two ways.)
有50kg糖水，按糖与水的比为3：7配成，糖水中含糖几千克？(用两种方法做．)
<gadget id="calculator">3 + 7</gadget>
<output>10</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">50 * (3/10)</gadget>
<output>15</output>

<result>15</result>