Pi = price/lb of italian

Pb = price/lb of brazillian

Wi = weight of italian

Wb = weight of brazillain

Pm = price/lb of mix

Wm = weight of mix

Pi * Wi + Pb * Wb = Pm * Wm

The only variables we don’t know is Wi and Wm so we plug the other variables into the eq.

Wm is the total weight so we have:

Wm = Wi + Wb

Plug all the values we know plus that equation into the original eq and we get:

Pi * Wi + Pb * Wb = Pm * (Wi + Wb)

$5 * Wi + $4 * 20lbs = $4.20 * (Wi + 20lbs)

And now we solve for Wi

5 * Wi + 4 * 20 = 4.2 * (Wi + 20)

5 * Wi + 80 = 4.2 * Wi + 84

5 * Wi – 4.2 * Wi = 4

0.8 * Wi = 4

Wi = 5

So you would need 5lbs of Italian roast.

i = # pounds of Italian coffee

2) Write equation:

** For each term (Italian, Brazillian, & mixture), multiply the amount of that type you have by the price of the type to get how much that type is worth.

** Note that you have 20 + i pounds of the blend

5i + 4 ( 20) = 4.20 ( 20 + i)

3) Solve

5i + 80 = 84 + 4.20i

.80i = 4

i = 5 pounds