:
The CoffeeShop is creating a new blend of coffee. Coffee A sells
for $5 per pound. Coffee B sells for $9 per pound. The
Coffee Shop will mix 20 pounds of the new blend and sell it for $6
per pound. The following equations represent the problem of
keeping the cost of the blend consistent with the Ingredients.
a + b = 20
5a + 9b = 120
a = pounds of Coffee A and b = pounds of Coffee B
How many pounds of Coffee B should be used in the blend?

Let x = pounds of $12 per pound coffee

then

20-x = pounds of $9 per pound coffee

.

12x + 9(20-x) = 10(20)

12x + 180 - 9x = 200

3x + 180 = 200

3x = 20

x = 20/3

x = 6 and 2/3 pounds of $12 per pound coffee

.

Amount of $9 per pound coffee:

20-x = 20-20/3 = 60/3 - 20/3 = 40/3

or

13 and 1/3 pounds of $9 per pound coffee

step-by-step explanation:

given perimeter: 28cm

length: 9cm

atp,

2(l+w)=p of the reactangle

2(9+x)=28

18+2x=28

2x=28-18

x=10/2

x=5

therefore width is 5 cm