Hi!
To solve this, first we should group like terms together.
1d - 2d - 10 + 7 = 8 - 10 + 1d - 3d
Simplify
-1d - 10 + 7 = 8 - 10 - 2d
-1d - 3 = -2 - 2d
Add 3 to both sides.
-1d - 3 + 3 = -2 + 3 - 2d
-1d = 1 - 2d
Add 2d to both sides.
-1d + 2d = 1 - 2d + 2d
1d = 1
Divide by 1 on both sides.
1d/1 = 1/1
d = 1
The answer is d = 1
Hope this helps!