Pythonで分数を約分するコード

def reduction(num,num2):
    '''Extract common divisor    
    '''
    tmp_num = num
    tmp_num2 = num2
    array = []
    min_int = num if num < num2 else num2
    b = True
    tmp = None
    while b:
        for i in range(2,min_int+1):
            if num % i == 0 and num2 % i == 0:
                num = num / i
                num2 = num2 / i
                if tmp == None:
                    tmp = i
                else:
                    tmp = tmp * i
                break
            if i == min_int:
                b =False

    num = int(tmp_num /tmp)    
    num2 = int(tmp_num2 /tmp)
    return num,num2

num,num2 = reduction(28,35)
print(num,end="/")
print(num2)