If the cost of corn varies directly with the number of ears purchased, and 6 ears cost 9 dollars, how many ears would cost 162 dollars

Let cost of corn = c,
no. of ears purchased = e

c varies directly as e
so
c = ke
when e = 6, c = 9
so, 9 = 6k
or k = 9/6 = 3/2.

when c = 162
c = ke
162 = 3/2 e
e = 162*2/3 = 54*2 = 108.

hence, 108 ears will cost 162$.