### This script uses the equivalent weight of the binder, curative, and castor oil
### to calculate the fractions of HTPB and curative, given the sum of HTPB/curative
### and fraction of castor oil

import numpy as np

#inputs, example numbers given
EW_curative = 178
EW_HTPB = 1234.6
EW_castor_oil = 164
frac_HTPB_curative = .1428
frac_castor = .003

#calculation - solving linear equation
inputs = np.array([EW_curative, EW_HTPB, EW_castor_oil, frac_HTPB_curative, frac_castor])
W_c = (((inputs[0]*inputs[3])/inputs[1]) + ((inputs[0]*inputs[4])/inputs[2]))/(1 + inputs[0]/inputs[1])

#outputs
print('Fraction curative:', round(W_c, 5))
print('Fraction HTPB:', round(inputs[3]-W_c, 5))
print('Fraction HTPB + Curative:',inputs[3])