Solve the system of equations
a + b = 10
a - b = 2
Aa = 5, b = 5
Ba = 2, b = 8
Ca = 6, b = 4
Da = 3, b = 7
a + b = 10
a - b = 2
Aa = 5, b = 5
Ba = 2, b = 8
Ca = 6, b = 4
Da = 3, b = 7