You add 7/5 to a number by mistake instead of taking it away, and you get 81/20. Find the value correctly calculated.
81/20 7/5 [OP_SUB] 7/5 [OP_SUB]
var_a = 4.05
var_b = 1.4
var_c = var_a - var_b
var_d = 1.4
var_e = var_c - var_d
print('{:.2f}'.format(round(var_e+1e-10,2)))