Hey there!
This grocer is mixing two kinds of coffee. I always love the smell of coffee!
We will say that x sells for $1.15 per pound and y sells for $2.75 per pound.
Altogether there are 24 pounds of coffee he is selling.
The algebraic equation would be x + y = 24
At $1.30 per pound, he will make 24 * $1.30 = $31.2
So, how many of the x and y kinds of coffee should he use to make the $1.30 per pound mixture which will net him $31.2?
The algebraic equation would be 1.15x + 2.75y = 31.2
We now have two equations :
x+y = 24
1.15x + 2.75y = 31.2
Substituting x= 24 -y in the second equation gives us
1.15(24-y) + 2.75y = 31.2
27.6 - 1.15y + 2.75y = 31.2
27.6 + 1.6y = 31.2
1.6y = 31.2 - 27.6
0.3y= 3.6
y= 2.25
x + y = 24
x + 2.25 = 24
x = 24 -2.25
x = 21.75
If y=2.25, then x= 21.75 as well.
So, he will use 21.75 pounds of the $1.15 per/lb one and another 2.25 pounds of the $2.75per/lb one.
~Done~