Help with math problem!!!!!

My daughter is having hard time with this math problem. I cannot figure out how to solve this. I wish I could but I cant.

Here is the three problems.
1.Solve by the substitution method.
3x-5y=4
y=4x-28

2. Solve by the addition method.
4x+7y=6
9x-2=49

3. Solve by the substitution method.
x+3y=15
2x-3y=3

That is all problems I need help with. Also, please write the steps by steps with
answer. Please. My daughter needs to learn how to do it exactly. I need the
answer before tomorrow. Please!!

1) If we re-write the first equation using the value of y from the 2nd:
3x - 5(4x - 28) =4
3x -20x +140 =4
-17x=-136
x=8
Sub this in 1st 3x8 - 5y =4
So 20 = 5y
y=4

2)
4x+7y=6
9x-2y=49

Multiply 1st by 2 and 2nd by 7:
8x+14y=12
63x-14y=343
Adding gives 71x = 355 so x=5
Sub in 4x+7y=6 gives 20+7y=6
7y = -14
y = -2

3)
x+3y=15
2x-3y=3

From 1st equation we get x = 15 -3y
Sub this in the 2nd
2(15 -3y) - 3y =3
30 - 6y -3y =3
- 9y = -27
y = 3
so 2x -9 =3
2x =12
x=6

Hope this helps you both:)