50 pounds of cashews and 71 pounds of walnuts were sold.
Our system of equations is
p+n = 121
p+4.19n = 280.50
Since the coefficients of p are the same, we will begin solving this by subtracting the second equation from the first:
![\left \{ {{p+n=121} \atop {-(p+4.19n=280.50)}} \right. \\ \\-3.19n = -159.50](https://img.qammunity.org/2019/formulas/mathematics/middle-school/8uqwbg7zidzxxd2mnngvfmz2afa0uxytzt.png)
Divide both sides by -3.19:
-3.19n/-3.19 = -159.50/-3.19
n = 50
There were 50 pounds of cashews sold.
To find the value of p, the pounds of walnuts, substitute 50 in for n in the first equation:
p+n = 121
p+50 = 121
Subtract 50 from both sides:
p+50-50 = 121-50
p=71
71 pounds of walnuts were sold.