Teacher Li used 10kg of salt water with a salt content of 15%, and diluted it with water to prepare a salt water with a salt content of 10% for scientific experiments. How much water should be added?
李老师用含盐率为15%的盐水10千克，加水稀释配制含盐率为10%的盐水用于科学实验，需加水多少千克？
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(3/20) / (1/10)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">10 * (3/2)</gadget>
<output>15</output>

<gadget id="calculator">15 - 10</gadget>
<output>5</output>

<result>5</result>