A boy read 3/4 of the book on Monday and 4/5 of the remainder on Tuesday .if there were 30 pages unread how many pages did the book contains
number of pages ==== x
(3/4)x + (4/5)(1/4)x + 30 = x
3x/4 + x/5 + 30 = x
times 20
15x + 4x + 600 = 20x
solve for x