To find what x value will be needed to get a 900 for y, we just have to rewrite the equation in order to isolate x on one side, then replace 900 for y and calculate the value of x, we can do it like this:
y=25x+150 , subtract 150 on both sides
y - 150 = 25x + 150 - 150
y - 150 = 25x, divide both sides by 25
(y-150)/25 = 25x/25
(y-150)/25 = x
Now we can calculate the value of x from the expression:
[tex]x=\frac{y-150}{25}[/tex]Now let's replace 900 for y:
[tex]x=\frac{900-150}{25}=\frac{750}{25}=30[/tex]Then, the value of x needed to get 900 for y is 30