Răspuns:
p=18
Explicație pas cu pas:
Notez cu p-nr de prajituri
I nepot mananca p/3
rest p-p/3=2p/3
II nepot mananca 2p/3:3=2p/3* 1/3=2p/9
rest 8
scriu ecuatia
p/3+2p/9+8=p ( aduc la acelasi numitor)
3p/9+2p/9+72/9=9p/9
3p+2p+72=9p
5p+72=9p
9p-5p=72
4p=72
p=72/4
p=18 a pregatit bunica