# How do you solve this system of equations by substitution: # - x+y = 40 and y = 9x#?

##### 2 Answers

Dec 10, 2017

#### Explanation:

Substitute value of

(1)

Now substitute this value of

Dec 10, 2017

#### Explanation:

#-x+y=40to(1)#

#y=9xto(2)#

#color(blue)"substitute "y=9x" into equation "(1)#

#-x+9x=40#

#rArr8x=40#

#"divide both sides by 8"#

#(cancel(8) x)/cancel(8)=40/8#

#rArrx=5#

#"substitute this value into equation "(2)#

#y=9xx5=45#

#rArr"point of intersection "=(5,45)#