Please help!

Assuming you mean the seperate equations:

 

6y + 4 = 2(3y - 5)

Simplify

6y + 4 = 6y - 10

Subtract 6y from both sides

4 = -10

No solution

 

20f + (-8f - 15) = 2(4f - 5)

Simplify

20f -8f - 15 = 8f - 10

Simplify again

12f - 15 = 8f - 10

Subtract 8f from both sides

4f - 15 = -10

Add 15 to both sides

4f = 5

Divide by 4 on both sides

f = 4/5

 

3(1 + 2f) - 5 = 6f - 2

Simplify

3 + 6f - 5 = 6f - 2

Subtract 6f from both sides

3 - 5 = -2

Simplify

-2 = -2

Add 2 to both sides

0 = 0

Infinite Many Solutions

 

7x + 5 = 10(x - 7) - 3x

Simplify

7x + 5 = 10x - 70 - 3x

Simplify

7x + 5 = 7x - 70

Subtract 7x from both sides

5 = -70

No Solution

 

I'm not entirely sure this is correct, but I hope this helps :)