There are 450 students in the sixth grade of Yucai Primary School, 60% of whom have reached the national physical exercise standard. If the sixth grade compliance rate reaches 80%, how many students should reach the standard?
育才小学六年级有学生450人，其中有60%达到国家体育锻炼标准，要使六年级达标率达到80%，还应有多少人达标？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(4/5) - (3/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">450 * (1/5)</gadget>
<output>90</output>

<result>90</result>