Answer:
The correct matrices are:
Matrix:
7 1 5
1 5 7
5 7 1
all diagonal elements of A^2 are: 7^2 + 1^2 + 5^2
Matrix:
9 18 27
27 -9 18
18 27 9
all diagonal elements of A^2 are: 9^2 + 27*18 + 18*27 or (-9)^2
Matrix:
8 1 6
6 8 1
1 6 8
all diagonal elements of A^2 are: 8^2 + 6*1 + 1*6
3( x - 1 ) = 2 x + 5
Expand 3(x-1) :
3*x - 3 x 1
3 x - 3 = 2 x + 5
Add 3 both sides :
3 x - 3 + 3 = 2 x + 5 + 3
3 x = 2 x + 8
3x - 2 x = 8
x = 8
hope this helps!
Assuming that the 120 faces have all numbers from 1 to 120 printed on them, we have a dice that can output all numbers between 1 and 120 with the same probability of 1/120.
So, the expected value is

15% of $7 is $1.05
7 x 74 = 518
1678 + 518 = 2196
She will earn $2196 in those 2 weeks