This year, Yujeong is 12 years old and her mother is 42 years old. In what year was her mother's age 4 times her age?
12 4 [OP_MUL] 42 [OP_SUB] 4 1 [OP_SUB] [OP_DIV]
var_a = 12
var_b = 4
var_c = var_a * var_b
var_d = 42
var_e = var_c - var_d
var_f = 4
var_g = 1
var_h = var_f - var_g
var_i = var_e / var_h
print(int(var_i))