X- 3y = -20
x - 5y = -40

and show how you got to the answer

X=3y-20 sooo

(3y-20)-5y=-40
-2y-20=-40
-2y=-20
y=10 sooo

x-3(10)=-20
x-30=-20
x=10

so x and y both equal 10

X=10 & Y=10.

Multiply the second equation by -1, it becomes  (-X+5=40)

Add it to the first so that to eliminate X

You will get 2Y = 20 & Y = 10. Plug the value of Y in any of the 2 equation & you will get X = 10

A) for the n row: 22+(n-1)×6therefore,b) 100-22=78that means (n-1)×6=7878÷6=1313+1=1414th row has 100 seats