so a number is represented as x
so
sum is add
sum of a number and negative 3
(x+-3)
mutiplied by that number
(x-3)x
distribute
a(b+c)=ab+ac
x(x-3)=x^2-3x
linear is if the degree (power) of the placeholder is equal to 1
x^2
2 is not equal to 1
it is 2nd degree and NOT linear
it is NOT LINEAR
