If an elevator starts at 120 meters (m) above the ground and descends at a speed of 4 meters (m) per second without stopping, find how many seconds after departure it will reach 20 meters (m) above the ground.
120 20 [OP_SUB] 4 [OP_DIV]
var_a = 120
var_b = 20
var_c = var_a - var_b
var_d = 4
var_e = var_c / var_d
print(int(var_e))