Explanation:
Let
x
be the kg of coffee of brand A in the mix and
y
be the kg of coffee of brand B in the mix.
The total kg must be
50
.
x
+
y
=
50
The cost per kg of the mix must br
$
7.20
. For this, the total cost of the mix will be
6
x
+
8
y
, so the total cost per kg of the mix will be
6
x
+
8
y
50
.
6
x
+
8
y
50
=
7.20
Now that we have our two equations, we can solve.
6
x
+
8
y
=
7.20
⋅
50
6
x
+
8
y
=
360
From the first equation, we can multiply both sides by
6
to get:
6
x
+
6
y
=
300
Subtracting, we get:
2
y
=
60
y
=
30
Thus, we need
30
kg of brand B in our mix. This means that
50
−
30
=
20
kg will be of brand A.