Question 442274
let us use x pounds of coffee total cost 10x cost of 40 lbs at $80=3200

total pounds=40+x  total cost = 30(40+x)
10x+3200=30(40+x)=1200+30x
2000=30x-10x=20x
100=x

so we mix 100lbs at $10 with 40lbs at $80
total cost 3200+1000=4200
total lbs =100+40=140
cost =$30  Ans