All the questions are similar but I need help

2. Explain and correct the error made by a student who simplified this expression.
–2x + 7x + 8
(–2 + 7 + 8)x
13x

3. Explain and correct the error made by a student who simplified this expression.
–2 + 7(x + 8)
5(x + 8)
5x + 40

4. Explain and correct the error made by a student who simplified this expression.
–2x – 4x + 8y – y
(–2 – 4)x + (8 – 0)y
–6x + 8y