Question

Solve the system of equations
3x+4y=10
3x-4y=20

Answer 1

Answer:

x = 5

y = -1.25

Step-by-step explanation:

3x+4y=10

3x-4y=20

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

6x=30

x=5

3(5)-4y=20

15-4y=20

-4y=5

y=-1.25

Answer 2

Answer:

(5, -5/4)

Step-by-step explanation:

3x+4y=10  

3x-4y=20

Add the two equations together to eliminate y

3x+4y=10  

3x-4y=20

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

6x = 30

Divide by 6

6x/6 = 30/x

x = 5

Now we need to find y

3x+4y =10

3(5) +4y = 10

15 +4y = 10

Subtract 15 from each side

15-15 +4y = 10-15

4y = -5

Divide by 4

4y/4 = -5/4

y = -5/4

(5, -5/4)