Answer :
[tex]dozen=12\ \ \ \ 5*12=60\\\\ 8\ oranges\ cost\ 1\$\\ 60\ oranges\ cost\ x\\\\ make\ proportion:\\ 8-1\\60-x\\\\cross\ multiplication\\\\ 8x=60\ \ \ | divide\ by\ 8\\\\ x=7.5\$\\\\5\ dozens\ cost\ 7.5\$\\\\[/tex]