12c + 12 (3/4c) + 12 (1/2c) shows the total cost for buying 3 phones that each cost c dollars per month for 12 months.

c(12 + 9 + 6)

12(2.25c)

Step-by-step explanation:

12c + 12 (3/4c) + 12 (1/2c)

12(1c) + 12(3/4c) + 12 (1/2c)

12(c + 3/4c + 1/2c)

12(2 1/4c)

12(2.25c)

Or

12c + 12 (3/4c) + 12 (1/2c)

12c + 9c + 6c

c(12 + 9 + 6)

1 is b and 2 is d

step-by-step explanation:

{x = -1/2 ,   y = -1

step-by-step explanation:

solve the following system:

{2 x + y = -2

{10 x - 3 y = -2

in the first equation, look to solve for y:

{2 x + y = -2

{10 x - 3 y = -2

subtract 2 x from both sides:

{y = -2 x - 2

{10 x - 3 y = -2

substitute y = -2 x - 2 into the second equation:

{y = -2 x - 2

{10 x - 3 (-2 x - 2) = -2

10 x - 3 (-2 x - 2) = (6 x + 6) + 10 x = 16 x + 6:

{y = -2 x - 2

{16 x + 6 = -2

in the second equation, look to solve for x:

{y = -2 x - 2

{16 x + 6 = -2

subtract 6 from both sides:

{y = -2 x - 2

{16 x = -8

divide both sides by 16:

{y = -2 x - 2

{x = -1/2

substitute x = -1/2 into the first equation:

{y = -1

{x = -1/2

collect results in alphabetical order:

answer:   {x = -1/2 ,   y = -1