It took 4 days to solve all the problems in the workbook. On the first day, I solved 1/2 of the total. On the second day, I solved 1/4 of the total. On the third day, I solved 1/6 of the total. When I solved 20 problems on the last day, find the total number of problems in the workbook.
20 1 1/2 1/4 [OP_ADD] 1/6 [OP_ADD] [OP_SUB] [OP_DIV]
var_a = 20
var_b = 1
var_c = 0.5
var_d = 0.25
var_e = var_c + var_d
var_f = 0.16666666666666666
var_g = var_e + var_f
var_h = var_b - var_g
var_i = var_a / var_h
print(int(eval('{:.2f}'.format(round(var_i+1e-10,2)))))