1224 / 12 = 102
He will be paying $102 a month for his TV
The equation of the line has the form: y = ax+b parallel to the line y = -2x + 7
=> a= -2
Passes through (4,1) => x=4, y=1
Substituting into the equation:
1= -2x(4) + b => b= 9
=> y= -2x + 9
Here you have a system of 2 equations and 2 unknowns. An easy way to solve this type is to isolate one of the variables.
12a + 2b = 8
2b = 8 - 12a
b =

b = 4 - 6a
Now plug 4 - 6a into equation 1 to solve for a.
a + 5(4 - 6a) = 19
a + 20 - 30a = 19
-29a = -1
a = 1/29 (answer)
Now plug a into the equation for b
b= 4 - 6(1/29)
b= 110/29 (answer)