English exam and Math exam were conducted separately for a class of 120 students. The number of students who did not appear for the English exam is twice the number of students who did not appear for the Math exam. The number of students who passed the Math exam is twice the number of students who appeared but failed the English exam. If the number of students who passed the English exam is twice the number of students who appeared but failed the Math exam, then the number of students who appeared but failed the English exam is _________
Reveal answer
40Reveal solution
Let DNA (did not appear) for Math = . Then DNA for English = .
Let students who failed English = (so Math pass = ).
Let students who failed Math = (so English pass = ).
Math total: ... (1)
English total: ... (2)
Subtracting (2) from (1) gives , so .