Among the fractions (7/20), (8/25), (10/15), (12/15), how many fractions cannot be reduced to finite decimals?
在(7/20)、(8/25)、(10/15)、(12/15)这些分数中，不能化成有限小数的是多少．
<gadget id="calculator">10 / 15</gadget>
<output>2/3 = around 0.666667</output>

<result>2/3 = around 0.666667</result>