Using a system of equations, Brian should use 3 pounds of almonds and 9 pounds of hazelnut to make the mixture.
A system of equations is when two or more variables are related, and equations are built to find the values of each variable.
In this problem, the variables are:
Considering that he makes 12 pounds, at a price of 12 x 10.35 = $124.2, the equations are given as follows:
From the first equation, y = 12 - x, hence, replacing in the second:
10.8x + 10.2y = 124.2
10.8x + 10.2(12 - x) = 124.2
0.6x = 1.8
x = 1.8/0.6
x = 3
y = 12 - x = 12 - 3 = 9.
Brian should use 3 pounds of almonds and 9 pounds of hazelnut to make the mixture.
More can be learned about a system of equations at https://brainly.com/question/24342899
#SPJ1