You can reword the two equations as:
-5x-y=15 (Divide original value by 3)
-2x+6y=6
Then use elimination to find x:
-30x-6y=90 (Multiply by 6 to get y values to be same to cancel out)
-2x+6y=6
You're left with:
-32x=96. Which can then be solved to find x which is -3.
Then plug back in
-2x+6y=6
Now to: -2(-3)+6y=6.
Which reduces to 6+6y=6. So y=0.
To graph them, just reword the equations (yes once again) so that y is in front.
y=-5x-15 and y=(1/3)x+1
Step-by-step explanation:
mean score means the sum of all 6 scores divided by the number of games : 6.
sum6/6 = 15
sum6 = 15×6 = 90
(sum6 + x)/7 = 16
sum6 + x = 16×7 = 112
90 + x = 112
x = 22
they scored 22 points in the 7th game.
