5c this question is from Operating System

Consider a paging system with the page table stored in memory. a) If a memory reference takes 150 nanoseconds how long does a paged memory reference take? b) If we add a TLB and 77 percent of all page-table references are TLB hits, what is the effective memory reference time? (Assume that finding a page-table entry in the TLB takes zero time, if the entry is there.)