Respuesta :

tonb
Convert the info into equations:

6f + a = 80
5f + 3a = 84

Then substitute one into the other, such that you eliminate one variable:

6f + a = 80 => a = 80-6f
5f+ 3(80-6f) = 84 => 5f + 240 - 18f = 84 => -13f = -156 => f=12

so the fern is $12.