Question

Teas costing $7 per pound are to be mixed with teas costing $4 per pound to make a 30-pound mixture. If the mixture is to sell for $6 per pound, how many pounds of each kind of tea should be used?

Answer 1

e+c = 30; e = 30-c

e(7) + c(4) = 30(6)

(30-c)(7) + c(4) = 180

Answer 2

a+b = c ; a = c-b

ax + by = cz

(c-b)x + by = cz

cx - bx + by = cz

b(y-x) = c(z-x)

b = c(z-x)/(y-x) ; i dont think I could remember that to well :)

Answer 3

cheap stuff = (30)(-1)(-3) = 10 if its right :)

20(7) + 10(4) = 30(6) maybe?

140 + 40 = 180 .. its right