calculus show your work please!!!!!!?

Question

a manager wishes to reduce her prics for coffee by mixing 2 grades together. if she has 50 pds. of coffee which sell for 1.20 per pound how much cofee worth 80 cent per round must she mix with so that she can sell the final mixture for 1.00 per pound

Answer 1

50(1.20) + .80(x) = 1.00(x+50)

60 + .8x = x + 50

10 = .2x

50 = x

50 pounds of the cheaper coffee.