You could find the x and y-intercepts by isolating these variables on one side. We'll start by finding y.
15x+20y=1800
20y=1800-15x
y=(1800-15x)/20
Now, we insert this y into the original equation (substitution).
15x+20[(1800-15x)/2]=1800
Now we combine like terms and solve for x.
15x+(36000-300x/2)=1800
36000-300x/2=-15x+1800
36000-300x=-30x+3600
36000=270x+3600
32400=270x
x=120
So the x-intercept is 120. Now, we can either go through that long process again to find the y-intercept (which is really inefficient, and you probably won't have time to do so on a test), or we can just input the x value we got into the original equation.
15x+20y=1800
15(120)+20y=1800
1800+20y=1800
20y=0
y=0
I'm not 100% sure about the y being 0, but I'm pretty sure. Hope this helped.
