You mistakenly subtracted 7/3 from a number instead of adding it, so you got 3/2 as a result. How much is it if you calculate it correctly?
3/2 7/3 [OP_ADD] 7/3 [OP_ADD]
var_a = 1.5
var_b = 2.3333333333333335
var_c = var_a + var_b
var_d = 2.3333333333333335
var_e = var_c + var_d
print('{:.2f}'.format(round(var_e+1e-10,2)))