Question

Please help with these questions

Answer 1

Obviously, what you looking for is slopes. Now let's get started. 
6.) 7x-5y=20 You subtract 7x both sides.
    -7x      -7x
-5y=-7x+20  Then you divide -5 both sides (which is include -7 and 20).
y=7/5x-4 Simplify.
-8x-3y=12 Add 8x both sides because it's a negative number.
+8x    +8x
-3y=8x+12 Divide -3 both sides.
y=-8/3x-4 Simplify.
 And your point value is (0,-4).
7.) -x-4y=12 Add x both sides.
     +x     +x
-4y=x+12 Divide -4 both sides.
y=-1/4x-3 Simplify.
20x+80y=0 Subtract 20x both sides.
-20x      -20x
80y=-20x Divide 80 both sides. Here's a hint: 20/80 is same thing as 2/8, so 
                you don't have to do all that. 
y=1/4x Simplify. Here's another hint: I bet you wondering there's no y-                         intercept. The y-intercept is (0,0).
Both of the functions are parallel, so there's no solution. 
8.) 30x+50y-100=0 Add 100 both sides.
                +100  +100
30x+50y=100 Subtract 30x both sides. 
-30x       -30x
50y=-30x+100 Divide 50 both sides.
y=-3/5x+2 Simplify.
3x-15y-30=0 Add 30 both sides.
          +30 +30
3x-15y=30 Subtract 3x both sides.
-3x      -3x
-15y=-3x+30 Divide -15 both sides.
y=1/5x-2 Simplify.
And your point value is (5,-1).
I hope it helps.