Building project

Question

I must build building model for school and i want it to be in golden rule. One specific part must be 400mm but i dont know how much other dimensions should be. I need to know dimension of "D" so i could construct further. I would be very greateful if someone could solve this for me. Thanks.
2xD+40mm=A+B

B=5xD

A/B=1.61803

Answer 1

If you just want to solve that system of equations, here's how (assuming that x is a multiplication sign, since you didn't mention x being another variable):

 

Solve the second equation for D:

 

B = 5D

B/5 = D

 

Solve the third equation for A:

 

A/B = 1.61803

A = 1.61803B

 

Plug those values into the first equation and solve for B:

 

2D + 40 = A + B

2(B/5) + 40 = 1.61803B + B

0.4B + 40 = 2.61803B

40 = 2.21803B

18.03402 = B

 

Plug that value for B back into the other two equations:

 

B/5 = D

18.03402/5 = D

3.60680 = D

 

A = 1.61803B

A = 1.61803(18.03402)

A = 29.17959

 

So, A = 29.17959, B = 18.03402, and D = 3.60680.