8 tortillas as per the graph
Follow the X line to the right for 4 orders, now go up the Y line to the number of corn tortillas needed indicated by the dot
It won't go all the way up to 50, but to 49 at stage 13.
All you need to do is keep adding 3 for each stage until you get to 50, but in this case or problem, 49.
I hope this helps.=^D
