Solve the system of equations by substitution. 3x + y = 9z

-5x + 2y = -4z

What is the value for y from the first equation, that could be substituted into the second equation?

-9z + 3x
3z + 9x
9z - 3x
-3x - 9z

x = 1.27

y = 5.18

Step-by-step explanation:

to solve this system of  equation by simultaneous equation we say that let

3x+y=9 equation 1

-5x+2y=4 equation 2

from equation 1

3x+y=9 equation 1

y = 9 -3x equation 3

substitute the value of y = 9 -3x into equation 2

-5x+2y=4 equation 2

-5x + 2( 9 -3x) = 4

-5x + 18 - 6x = 4

collect the like terms

18 - 4 = 6x + 5x

14 = 11x

divide both side by 11

14/11 = 11x/11

x = 14/11

x = 1.27

put the value of x = 1.27 into  equation 3

y = 9 -3x equation 3

y = 9 - 3( 1.27)

y = 9 - 3.82

y = 5.18

to check if you are correct put the value of x and y into either equation 1 or equation 2.

3x+y=9 equation 1

3( 1.27) + 5.18 = 9

3.81 + 5.18 = 9

9 = 9

answer: 21$

step-by-step explanation:

$42 / $14 = 3   (ratio 3: 1)

$7 x 3 = $21