6d 1 = 15-d i really don't understand thi and my teacher won't

You required to find the value of d.
Always remember the concept that if you transpose "+" sign to the other side, it becomes "-" sign, and vice versa. Make sure that you arrange the like terms and constants. Solving the equation,
6d + 1 = 15 - d
6d + d = 15 - 1
7d = 14
d = 14/7 = 2

When transposing a multiplication, you divide it to the other side.

Verifying the solution,
6(2) + 1 = 15 - 2
12 + 1 = 13
13 = 13

x = 11

Step-by-step explanation:

-3x + 4 = -29

step one : subtract 4 from both sides

-3x = -29 - 4

-3x=-33

step two : divide -3 from both sides

-33 ÷ -3 = 11

x = 11

check your work now

-3(11) + 4 = -29

-3 x 11 = -33

-33 + 4 = -29