solvEquation | Python Fiddle

def tokenizer(expr, tokens):
       
        termo = ""
        lstTermos = []
       
        for e in expr:
           
            if e in tokens:
                lstTermos += [termo]
                if e != "=":
                    termo = e
                else:
                    termo = ""
                    lstTermos += ["="]
               
            else:
                termo += e
           
           
        lstTermos += [termo] 
        return lstTermos
     
    #def lexicor(eq):
    def dictEq(eq):
        side = 'left'
        dct = {'left':[], 'right':[]}
       
        for e in eq:
                
            if e == '=':
                side = 'right'
            else:
                dct[side] += [e]
           
        return dct           
     
    def removeItemFromList(lst, items):
        for i in items:
            lst.remove(i)
     
        return None
     
    def organizerSides(dct):
       
        lstLeftItemsToRemove=[]
        lstRightItemsToRemove=[]
        lstLeftItems = []
        lstRightItems = []
       
        #Look at the left side and move all constants to the right side of the equal sign
        for e in dct['left']:
            if e.count('x') == 0:
               
                if (-1)*int(e)> 0:
                    sign = '+'
                else:
                    sign = ''
               
                lstRightItems += [sign+str((-1)*int(e))]   
                lstLeftItemsToRemove += [e]
        removeItemFromList(dct['left'],lstLeftItemsToRemove)
        dct['right'] += lstRightItems
       
        #Look at the right side and move all variables to the left side of the equal sign
        for e in dct['right']:
            if e.count('x'):
                coeficiente = int(e.strip('x'))
                if (-1)*coeficiente > 0:
                    sign = '+'
                else:
                    sign = ""
                lstLeftItems += [sign + str((-1)*coeficiente)+'x']
                lstRightItemsToRemove += [e]
               
        removeItemFromList(dct['right'], lstRightItemsToRemove)
        dct['left'] += lstLeftItems
       
        return dct['left'], dct['right']
     
     
    equation = "7x+111=15-3x+78"
    #eq = tokenizer("3x+1-9x-18+44=4x-90","+-=")
    eq = tokenizer(equation,"+-=")
    print equation
    leftEq, rightEq = organizerSides(dictEq(eq))
    print rightEq
    print ''.join(leftEq)+"="+''.join(rightEq)
    sLeft = 0.0
    sRight = 0.0
    for e in leftEq:
        sLeft += int(e.strip('x'))
    for e in rightEq:
       
        sRight += int(e)
       
    print str(sLeft)+"x="+str(sRight)
    print "x="+str(sRight)+"/"+str(sLeft)
    print "x=", sRight/sLeft

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