Given the scalar equation, 8x + 9y = -45, write a vector equation? scalar equation: 
8x + 9y = -45
Attempt:
I took the y-intercept and the x-intercept of the scalar equation and got
(-5.625, 0) and (0,-5)
By subtracting the points i got [5.625, -5]
so my vector equation was 
[x,y] = [0,-5] + t[5.625, -5]
the correct answer is
[0,-5] + t[-9,8]
How did they get this??? Am i doing something wrong?

You did nothing wrong, but the answer uses $[-9,8]$ instead of $[5.625,-5]$.
This is because $$5.625\times (-1.6)=-9,$$$$-5\times (-1.6)=8.$$ We can do this because we have a parameter $t$ in front of this orientation vector.
