Xiaohong goes to a stationery store to buy a calculator and finds that a calculator is being sold at 80% of the original price at 6.4 yuan. After bargaining, the salesperson finally agrees to sell it at 70% of the original price. How much did Xiaohong pay for this calculator?
小红到文具店买计算器，发现一种计算器现在按原价80%出售，售价6.4元，经过讨价还价，营业员最终同意按70%售出，小红买这个计算器用了多少元？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">6.4 / (4/5)</gadget>
<output>8</output>

<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">8 * (7/10)</gadget>
<output>28/5 = around 5.6</output>

<result>28/5 = around 5.6</result>