For 1, the answer is D because:
-10x + 5y = 40
add 10x to both sides
5y = 10x + 40
divide by 5
y = 2x + 8, In the equation y=mx+b, b is the y-intercept so then 8 is your y-intercept. To find the x-intercept you just plug in 0 for y and then solve for x:
0 = 2x + 8
subtract 8 from both sides
-8 = 2x
divide by 2
-4 = x, so the x-intercept is -4.
For 2, the answer is D because:
5x + 4y = 80
subtract 5x from each side
4y = -5x + 80
divide by 4
y = -5/4x + 20, In the equation y=mx+b, b is the y-intercept so then 20 is your y-intercept. To find the x-intercept you just plug in 0 for y and then solve for x:
0 = -5/4x + 20
subtract 20 from each side
-20 = -5/4x
multiply each side by 4
-80 = -5x
divide by -5
16 = x.
