After 20 minutes he is on page 120 after 45 minutes he is on page 178how many pages did he read before study hall

The total number of pages read by him before study hall is 178.

Step-by-step explanation:

Given as:

The total number of page read after 20 min = 120 pages

After 45 min of reading, he is on page number 178

Let The total number of pages read by him = n

Now, Since after 45 min of reading he is on page number 178

so, After page number 120, he started reading from page number 121 and read up to page number 178

Or, The number of pages between page number 178 and page number 120 = (178 - 121) + 1

Or, The number of pages between page number 178 and page number 120 = 57 + 1

Or, The number of pages between page number 178 and page number 120 = 58

So, The total number of pages he read in all = The total number of page read after 20 min + number of pages he read for 45 min

∴ n = 120 + 58

I. e n = 178

The total number of pages read by him = n = 178

Hence The total number of pages read by him before study hall is 178. Answer