Answer:
expression for total cost is given by

Step-by-step explanation:
Here we need to find the expression for the total cost
Let us find the cost for x pounds of peanut , y pounds of cashews and z pounds of almonds
cost of 1 pound of peanut = $3.95
cost of x pounds of peanut = $3.95x
cost of 1 pound of cashews = $4.25
cost of y pounds of cashews = $4.25y
cost of 1 pounds of almonds = $5.99
cost of z pounds of almonds = $5.99z
total cost = 
cost after 20% off = total cost - 20% of total cost
= 80% of total cost
cost after 20% off =80%
cost after 20% off =
now we can plug x= 2 , y= 3 and z=1
so we have
cost after 20% off =
=$ 21.31