The main components of honey are fructose and glucose, which account for more than (3/5) of the total mass of honey. There is a kind of honey in which fructose and glucose account for 4/5 of the total amount of honey. If there is 3.5kg of this honey, how many kilograms of fructose and glucose are there in total?
蜂蜜最主要的成分是果糖和葡萄糖，果糖和葡萄糖的质量占蜂蜜总质量的(3/5)以上．有种蜂蜜，果糖和葡萄糖的质量占蜂蜜总量的(4/5)，如果有3.5kg的这种蜂蜜，其中的果糖和葡萄糖共有多少千克？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">3.5 * (4/5)</gadget>
<output>2.8</output>

<result>2.8</result>