It takes 10 days for an older sister and 20 days for a younger sister to complete a certain task. After the older sister did this task alone for four days, the sisters worked together to finish the task. How many days did the sisters work together?
1 4 10 [OP_DIV] [OP_SUB] 1 10 [OP_DIV] 1 20 [OP_DIV] [OP_ADD] [OP_DIV]
var_a = 1
var_b = 4
var_c = 10
var_d = var_b / var_c
var_e = var_a - var_d
var_f = 1
var_g = 10
var_h = var_f / var_g
var_i = 1
var_j = 20
var_k = var_i / var_j
var_l = var_h + var_k
var_m = var_e / var_l
print(int(eval('{:.2f}'.format(round(var_m+1e-10,2)))))