The unit price of a certain brand of mobile phone is 980 yuan. During the promotion, it is sold at a 15% discount. How much is it cheaper?
某品牌的手机单价是980元，促销时，按八五折出售，便宜多少元．
<gadget id="calculator">85 / 100</gadget>
<output>17/20 = around 0.85</output>

<gadget id="calculator">980 * (17/20)</gadget>
<output>833</output>

<gadget id="calculator">980 - 833</gadget>
<output>147</output>

<result>147</result>