25: a = 15: 75, 100: 9.6 = 15: b, a+b = how much.
25：a=15：75，100：9.6=15：b，a+b=多少．
<gadget id="calculator">25 * 75</gadget>
<output>1_875</output>

<gadget id="calculator">1_875 / 15</gadget>
<output>125</output>

<gadget id="calculator">15 * 9.6</gadget>
<output>144</output>

<gadget id="calculator">144 / 100</gadget>
<output>36/25 = around 1.44</output>

<gadget id="calculator">125 + (36/25)</gadget>
<output>3_161/25 = around 126.44</output>

<result>3_161/25 = around 126.44</result>