Isaac uses the fermi process to estimate the number of playing cards it would take to cover his backyard. both the cards and his backyard are rectangular in shape.

he estimates the playing cards to be about 3 in. long and 2 in. wide.
he estimates his backyard to be about 40 ft long and 20 ft wide.

which expression should isaac use in the process?

i got 8×10^2 / 6×10^0 but apparently, that's wrong.