import numpy as np
A = np.mat(""" 0.07 0.18 0.15 0.24 ; 
                 0.04 0.24 0.10 0.65 ; 
                 0.54 0.42 0.54 0.10 ; 
                 0.35 0.16 0.21 0.01""")
b = np.array([10.5, 17.5, 28., 14.])


x = np.linalg.solve(A, b)
y = ['D1', 'B1', 'D2', 'B2']

print 'La solución es:'
for t in zip(y, x):    
    print "%s = %.2f" % t