The cost of a television is $429.99 after sales tax is added. if the sales tax is 7.5%, what was the cost of the television before sales tax was added? (a) $377.74 (b) $389.46 (c) $397.74 (d) $399.99 (e) $459.27

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18