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