For a batch of corn seeds, the ratio of the number of germinated grains to the number of ungerminated grains is 3.5:1.5. How much is the germination rate of this batch of seeds higher than the ungerminated rate of the total number of seeds in this batch?
一批玉米种子，发芽粒数与没有发芽粒数的比是3.5：1.5，这批种子的发芽率比未发芽率高这批种子总数的多少
<gadget id="calculator">3.5 - 1.5</gadget>
<output>2</output>

<gadget id="calculator">3.5 + 1.5</gadget>
<output>5</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>