Amy's grade was 90th percentile of the 80 grades for her class. Of the 100 grades from another class, 19 were higher than Amy's, and the rest were lower. If no other grade was the same as Amy's grade, then Amy's grade was what percentile of the grades of the two classes of two classes combined?
Choose the correct choice from the following choices: A) 72nd B) 80th C) 81st D) 85th E) 92nd
Being in 90% percentile out of 80 grades means Amy was 73rd (from the least grade) in the class (as long as nobody had Amy's grades), she outscored 72.   In another class her grade would rank her 82 (from the least grade out of 101, 100+Amy), 81 had the grades lower than Amy.   So in combined classes she outscored  72+81= 
<gadget id="calculator"> 72+81</gadget>
<output>153</output>
153. There are 180 students  153/180= 
<gadget id="calculator"> 153/180</gadget>
<output>17/20 = around 0.85</output>
0.85   Answer: 85th (85%)
<result>D</result>
Amy's grade was 90th percentile of the 80 grades for her class. Of the 100 grades from another class, 19 were higher than Amy's, and the rest were lower. If no other grade was the same as Amy's grade, then Amy's grade was what percentile of the grades of the two classes of two classes combined?