Answer:
Simplifying 
41 = 12d + -7 
 
Reorder the terms: 
41 = -7 + 12d 
 
Solving 
41 = -7 + 12d 
 
Solving for variable 'd'. 
 
Move all terms containing d to the left, all other terms to the right. 
 
Add '-12d' to each side of the equation. 
41 + -12d = -7 + 12d + -12d 
 
Combine like terms: 12d + -12d = 0 
41 + -12d = -7 + 0 
41 + -12d = -7 
 
Add '-41' to each side of the equation. 
41 + -41 + -12d = -7 + -41 
 
Combine like terms: 41 + -41 = 0 
0 + -12d = -7 + -41 
-12d = -7 + -41 
 
Combine like terms: -7 + -41 = -48 
-12d = -48 
 
Divide each side by '-12'. 
d = 4 
 
Simplifying 
d = 4