IIRC Walgreens prints larger than 8x10 at an a central facility, not at the local Walgreens store.
Walgreens store prints are usually made using a Fuji Frontier C-print mini lab machine and so are not inkjet prints.
My 10 MP, Nikon D200 delivers a 3:2 aspect ratio image that has image resolution of 3872 × 2592 pixels.
To print 36" wide - 3872 px / 36" = 107.5 PPI.
100 PPI is often the lowest print resolution a print lab will do, so a print will have sufficient quality their reputation won't suffer.
I know that Mpix, the consumer outlet of Miller Professional imaging, had/has a 100 PPI minimum print resolution.