Respuesta :

Ax4 = E
A = E/4

B/4 = E
B = 4E

C+4 = E
C = E-4

D-4 = E
D = E+4

E/4 + 4E + E-4 + E+4 = 25
25/4 E = 25
E = 25 * 4/25
E = 4