Question 236490
Makr has a 50 minute head start so will be on page 25 when Mindy starts 

30 * 5/6 = 25

30 pages per hour multiplied by time = page + 25 
40 pages per hour multiplied by time = page

OR

30t=p+25 (1)
40t=p    (2)

(2)-(1)

10t= 25

t = 2.5

After 2.5 hours they both will be on the same page.