2 level virtual memory meaning 2 level of page tables+1 main memory+1 secondary memory
now all necessary page tables reside in main memory itself...DO NOT ASSUME PAGE FAULTS WHEN FETCHING PAGES OF PAGE TABLES..
so what we do is after cpu generates virtual address we access 2 levels of page tables from main memory successfully then we get the frame number and finally access main memory the third time to see if that frame is already in there or not ..
if its there its cool else access secondary memory..
so....=> 2×10^(-8) + H×10^(-8) + (1-H)×(10^-3+10^-8)
=> 3×10^(-8) + (1-H)×10^(-3)
=> as it's in the selected answer of @Arjun sir.
now "80 % OF MAXIMUM VALUE"----- maximum value means what maximum access time including all probability (hit miss ratios and all included in computing).
now access efficiency meaning minimum time in ideal case..so 2 time main memory access for page tables and then 1 time agin main memory access for frame.
so, 3×10^(-8)=0.8×[ 3×10^(-8) + (1-H)×10^(-3)]
=> h=99.99%