X+y=20
x=-4+y how do i solve this equation by using substitution

The solutions is (8,12).

Step-by-step explanation:

The second equation is solved for x so we can replace the first x in the first equation with what the second x in the second equation equals.

That is we can do this:

x+y=20 where x=-4+y

(-4+y)+y=20

-4+y+y=20

Combine like terms:

-4+2y=20

Add 4 on both sides:

    2y=24

Divide both sides by 2:

      y=24/2=12

So if x=-4+y and y=12, then x=-4+12=8.

The solution is (8,12).

This means that (8,12) is a common point on both the given equations.

This means it will make both equations true when plugging it in.

x+y=20 with (x,y)=(8,12):

8+12=20 is true since 8+12 is 20.

x=-4+y with (x,y)=(8,12):

8=-4+12 is true since -4+12=8.

x > 1.3

step by step:

8.5−0.9x> 9.8−1.9x

step 1: simplify both sides of the inequality.

−0.9x+8.5> −1.9x+9.8

step 2: add 1.9x to both sides.

−0.9x+8.5+1.9x> −1.9x+9.8+1.9x

1x+8.5> 9.8

step 3: subtract 8.5 from both sides.

1x+8.5−8.5> 9.8−8.5

1x> 1.3

step 4: divide both sides by 1.

1x/1 > 1.3/1