Jihoon cut a fishing line to make a fishing rod. When you add 3.1 meters (m) to the current length of this fishing line, multiply it 3.1 times, and then multiply it again by 2.1 it becomes the length of the original fishing line. If the length of the fishing line of Ji-hoon's fishing rod is 8.9 meters (m), find the original length of the fishing line in meters (m).
8.9 3.1 [OP_ADD] 3.1 [OP_MUL] 2.1 [OP_MUL]
var_a = 8.9
var_b = 3.1
var_c = var_a + var_b
var_d = 3.1
var_e = var_c * var_d
var_f = 2.1
var_g = var_e * var_f
print('{:.2f}'.format(round(var_g+1e-10,2)))