3(n + 5) = 2 (n-1)

Firstly you get rid of the bracets

so 3n + 15 = 2n-2

Then you bring all the terms with n on one side and all the other numbers on the other side is

3n + -2n = -15-2

n = -17

3( 1/2 x-4)= 2 + 1/2(x+1)

same rule applies as above

so 3/2x - 12 = 2+ 1/2x + 1/2

3/2x-1/2x = 12 + 1/2

x = 25/2

2/3x+1=1/2x-3/4

2/3x-1/2x = -1-3/4

1/6x = -7/4

x = -21/2

4.1x +7.8 = 8.62

4.1x = 8.62-7.8

4.1x = 0.82

x= 0.2