First. Second. The average of the three numbers of C is 90, and their ratio is 3:5:2, so how much less is the number of A than the number of B.
甲．乙．丙三个数的平均数是90，它们的比是3：5：2，则甲数比乙数少多少．
<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">3 + 5 + 2</gadget>
<output>10</output>

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

<gadget id="calculator">90 * (3/10)</gadget>
<output>27</output>

<gadget id="calculator">2 * 27</gadget>
<output>54</output>

<result>54</result>