My workspace

import matplotlib.pyplot as plt
import numpy as np

x=[0, 30, 60, 90, 120, 150, 180, 210]
y=[1.00, 1.01, 1.03, 1.03, 1.04, 1.06, 1.07, 1.07]

coef = np.polyfit(x,y,1)
poly1d_fn = np.poly1d(coef) 
# poly1d_fn is now a function which takes in x and returns an estimate for y

plt.plot(x,y, 'yo', x, poly1d_fn(x), '--k')
plt.xlabel("Concentração")
plt.ylabel("Densidade")

plt.ylim(0.975, 1.10)

x=[0, 4, 8, 12, 16, 20, 24, 28, 32, 36]
y=[2.7, 10.8, 29.15, 50.4, 53.6, 54.1, 50.4, 54.7, 48.5, 51.4]
plt.plot(x, y, '--k')

import re

lista = ["32 + 698", "3801 - 2", "45 + 43", "123 + 49"]
def arithmetic_arranger(problems, show_answers = False):
    
    ## checar tamanho da lista
    if(len(problems) > 5):
        raise ValueError('Error: Too many problems.')
    
    problemas_formatados = list()

    ## obter o operador e numeros
    for problema in problems:
        operando1, operador, operando2 = problema.split()
        
        ## erros
        if(operador != "+" and operador != "-"):
            raise ValueError("Error: Operator must be '+' or '-'.")
            
        elif(len(operando1) > 4 or len(operando2) > 4):
            raise ValueError('Error: Numbers cannot be more than four digits.')
        
        elif(re.search("\D", operando1) or re.search("\D", operando2)):
            raise ValueError('Error: Numbers must only contain digits.')
            
        
        if(show_answers):
            ## resultado da conta
            if(operador == "+"):
                res = int(operando1) + int(operando2)
            else:
                res = int(operando1) - int(operando2)
            
            ## comprimento do problema
            comprimento = max(len(operando1), len(operando2), len(str(res))) + 2
        
            ## formata o problema
            problema_formatado_res = "{0:>{1}}\n{2} {3:>{4}}\n{5}\n{6:>{1}}".format(operando1, comprimento, operador, operando2, comprimento - 2, '-' * comprimento, res)

            ## adiciona o problema formatado à lista
            problemas_formatados.append(problema_formatado_res)  
        
        else:
            operando1, operador, operando2 = problema.split()

            comprimento = max(len(operando1), len(operando2)) + 2

            problema_formatado = "{0:>{1}}\n{2} {3:>{4}}\n{5}".format(operando1, comprimento, operador, operando2, comprimento - 2, '-' * comprimento)

            problemas_formatados.append(problema_formatado)
                
        
    print("    ".join(problemas_formatados))
 

arithmetic_arranger(lista)
    

lista1 = ["32 + 698", "3801 - 2", "45 * 43", "123 + 49"]
lista_op = list()
lista_num = list()

for conta in lista1:
        ind = conta.find("+")
        ind2 = conta.find("-")

        if(ind != -1):
            lista_op.append(conta[ind])
            lista_num.append(conta.split(" + "))

        elif(ind2 != -1):
            lista_op.append(conta[ind2])
            lista_num.append(conta.split(" - "))
            

if(len(lista_num) < len(lista1)):
    print(True)

print(lista_num)