Question

The sum of five times a number and -6 is -2

Answer 1

5n + (-6) = -2
add 6 to -2
5n = -2 + 6
5n = 4
divide both sides by 5
n = 4/5

Answer 2

Let' call the number 'M' for 'mystery number'.

The number . . . . .  M

Five times the number . . .  5 M

The sum of 5 times the number and  -6 . . .  5 M - 6

You said that's  -2 .  So I can write

                                         5 M - 6  =  -2

Add  6  to each side:      5 M       =   4

Divide each side by  5 :     M       =  4/5   or   0.8  .