Answer:
a. The slope is
and the y-intercept is 0
b. The slope is
and the y-intercept is

c. The slope is
and the y-intercept is 2
Explanation:
The easiest way to find the slope and y-intercept is to put each equation in the slope-intercept form
That is:
y = mx = c
where m is the slope and c is the y-intercept
Part a:
6(x+y) = 3(x-y)
2(x+y) = x-y
2x + 2y = x - y
3y = -x

Comparing this with the general formula, we can conclude that:
The slope is
and the y-intercept is 0
Part b:
2(x+y) = 5(y+1)
2x + 2y = 5y + 5
3y = 2x - 5

Comparing this with general formula, we can conclude that:
The slope is
and the y-intercept is

Part c:
5x + 10y -20 = 0
10y = -5x + 20

Comparing this with the general formula, we can conclude that:
The slope is
and the y-intercept is 2
Hope this helps :)