A*4=e b/4=e c+4=e d-4=e A+b+c+d=100

I believed you are looking for the value of e. The value of e is 16 below is the solution:

A*4 = E, so A=E/4

B/4 = E, so B=4E

C+4 = E, so C=E=4

D-4 = E, so D=E+4

and

A+B+C+D=100.

Substitute values of A, B, C and D in the equation, we get,

(E/4) + 4E + E-4 + E+4 = 100

(E/4) + 4E + 2E = 100

(E/4) + 6E = 100

(E+24E) / 4 = 100

E+24E = 100*4

25E = 400

E = 400/25

E = 16