Answer: 72%
Step-by-step explanation:
Set Jamal's original ring price = x
[tex]x - x(0.2) = 2640\\x(1-0.2)=2640\\x(0.8)=2640\\x=\frac{2640}{0.8}=3300[/tex]
Jamal's original ring price = $3300
Set Naomi's discount = y
[tex]3300-3300(y)=924\\=3300(1-y)=924\\1-y=\frac{924}{3300} \\-y=\frac{924}{3300} -1\\y=1-\frac{924}{3300}=1-0.28=0.72[/tex]
Naomi's discount is 0.72 = 72%