Solve the system of equations x + y = 4 and -9x + y = -84 by combining the
equations.

x= 44/5 and y=  -24/5

Step-by-step explanation:

step:solve

x+y=4  

x+y+−y=4+−y(Add -y to both sides)

x=−y+4

step:substitute

−y+4 for x in−9x+y=−84:

−9x+y=−84

−9(−y+4)+y=−84

10y−36=−84(Simplify both sides of the equation)

10y−36+36=−84+36(Add 36 to both sides)

10y=−48

10y/10 = -48/10      (Divide both sides by 10)

y= −24/  5  

step:substitute

-24/5 for y in x=-y+4:

x=-y+4

x=- -24/5+4

x= 44/5 (Simplify both sides of the equation)

false

step-by-step explanation:

the reason i say this is because for a certain length of sides you can pick any two and the length is wither equal or greater than the third side and in this case it's not.

3 + 5 = 8

8 is smaller than 9 which is the third side.

hope this : )