Question

- 7.5x - 1.2y = -2.7
- 1.5x + 1.2y = -3.3​

Answer 1

x = 2/3 , y = -23/12

Explanation:

Solve the following system:

{-7.5 x - 1.2 y = -2.7

{1.2 y - 1.5 x = -3.3

In the first equation, look to solve for x:

{-7.5 x - 1.2 y = -2.7

{1.2 y - 1.5 x = -3.3

-7.5 x - 1.2 y = -(15 x)/2 - (6 y)/5 and -2.7 = -27/10:

{-(15 x)/2 - (6 y)/5 = -27/10

Add (6 y)/5 to both sides:

{-(15 x)/2 = 3/10 (4 y - 9)

{1.2 y - 1.5 x = -3.3

Multiply both sides by -2/15:

{x = 1/25 (9 - 4 y)

{1.2 y - 1.5 x = -3.3

Substitute x = 1/25 (9 - 4 y) into the second equation:

{x = 1/25 (9 - 4 y)

{1.2 y - 0.06 (9 - 4 y) = -3.3

1.2 y - 0.06 (9 - 4 y) = 1.2 y + (0.24 y - 0.54) = 1.44 y - 0.54:

{x = 1/25 (9 - 4 y)

{1.44 y - 0.54 = -3.3

In the second equation, look to solve for y:

{x = 1/25 (9 - 4 y)

{1.44 y - 0.54 = -3.3

1.44 y - 0.54 = (36 y)/25 - 27/50 and -3.3 = -33/10:

(36 y)/25 - 27/50 = -33/10

Add 27/50 to both sides:

{x = 1/25 (9 - 4 y)

{(36 y)/25 = -69/25

Multiply both sides by 25/36:

{x = 1/25 (9 - 4 y)

{y = -23/12

Substitute y = -23/12 into the first equation:

Answer: x = 2/3 , y = -23/12

Answer 2

x = 2/3 y = -23/12

Explanation:

- 7.5x - 1.2y = -2.7

- 1.5x + 1.2y = -3.3​

Add the equations together

- 7.5x - 1.2y = -2.7

- 1.5x + 1.2y = -3.3​

---------------------------

-9x = -6

Divide each side by -9

-9x/-9 =-6/-9

x =2/3

Now we need to find y

-1.5 (2/3) +1.2y = -3.3

-1 +1.2y = -3.3

Add 1 to each side

-1+1 +1.2y = -3.3+1

1.2y = -2.3

Divide by 1.2

1.2y/1.2 = -2.3/1.2

y =-23/12