Minta. Tlng cara dan jwbn dr soal berikut 1 -5 ya makasih

1. 3n+5 = 20
3n = 20-5 
3n = 15
n = 5

2. 10-4n = 30
-4n = 30-10
-4n = 20
n = -5

3. 5-n = 10-2n
-n+2n = 10-5
n = 5

4. 55 = 5n+5
55-5 = 5n
50 = 5n
10 = n

5. 10n+10 =50
10n= 50-10
10n = 40
n = 4