Why does addition in this equation suddenly turn into division?

Question

Please help with the following

Problem: 0,105=0,083+0,44*RD(0,65). Solve for RD.

Solution: RD= (0,105-0,083)/(0,44*0,65)=0,22/0,286=0,769=7,69%

Question: Why does the + between 0,083 and 0,44 in the problem turn into division in the solution?

 

Answer 1

0.105 = 0.083 + 0.44(RD)(0.65)

 

Subtract 0.083 from both sides:  (0.105 - 0.083) = 0.44(RD)(0.65)

 

Divide both sides by 0.44:  (0.105 - 0.083)/(0.44) = (RD)(0.65)

 

Divide both sides by 0.65:  (0.105 - 0.083)/[(0.44)(0.65)] = RD

 

RD = 0.022/0.286 = 0.0769