At the market, 5 light bulbs cost $9.85.
How much do 7 light bulbs cost?

$13.79

Step-by-step explanation:

Divide the cost by the number of light bulbs.

$9.85 ÷ 5 bulbs = $1.97 each

Multiply the cost of each bulb(1.97) by each of the new bulbs.

$1.97 x 7 bulbs = $13.79

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