In a school’s grade 6 end-of-term math score, exercises accounted for 20%, monthly exams accounted for 30%, and finals accounted for 50%. Zhang Ming scored 80 points in practice, 85 points in monthly exams, and 90 points in the end-of-term. What is the total score of Zhang Ming’s final math evaluation ．
某校6年级期末数学总评成绩，练习占20%，月考占30%，期末占50%，张明练习得80分，月考得85分，期末得90分，张明期末数学总评多少分．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">80 * (1/5)</gadget>
<output>16</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">85 * (3/10)</gadget>
<output>51/2 = around 25.5</output>

<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">90 * (1/2)</gadget>
<output>45</output>

<gadget id="calculator">16 + (51/2) + 45</gadget>
<output>173/2 = around 86.5</output>

<result>173/2 = around 86.5</result>