from sympy import *
a1 = Symbol('a1')
a2 = Symbol('a2')
a3 = Symbol('a3')
b1 = Symbol('b1')
b2 = Symbol('b2')
r = solve([
    a1+a2-40,
    b1+b2-10,
    2*a1+4*b1-60,
    2*a2+4*b2-40
], [a1,a2,b1,b2])
print(r)