# Learn Interfaces by Building an Equation Solver - Step 24

### Tell us what’s happening:

the biggest mind boggle ever can someone help i know why this is wrong because its on the wrong side that’s why, but how the hell do i get it to go like 2x+3=0

### Your code so far

``````from abc import ABC, abstractmethod

class Equation(ABC):
degree: int

def __init__(self, *args):
if (self.degree + 1) != len(args):
raise TypeError(
f"'Equation' object takes {self.degree + 1} positional arguments but {len(args)} were given"
)
if any(not isinstance(arg, (int, float)) for arg in args):
raise TypeError("Coefficients must be of type 'int' or 'float'")
if args[0] == 0:
raise ValueError("Highest degree coefficient must be different from zero")
self.coefficients = {(len(args) - n - 1): arg for n, arg in enumerate(args)}

def __init_subclass__(cls):
if not hasattr(cls, "degree"):
raise AttributeError(
f"Cannot create '{cls.__name__}' class: missing required attribute 'degree'"
)

def __str__(self):
terms = []
for n, coefficient in self.coefficients.items():
if not coefficient:
continue
if n == 0:
terms.append(f'{coefficient:+}')
elif n == 1:
terms.append(f'{coefficient:+}x')

# User Editable Region

equation_string = ' =0'.join(terms)

return equation_string

# User Editable Region

@abstractmethod
def solve(self):
pass

@abstractmethod
def analyze(self):
pass

class LinearEquation(Equation):
degree = 1

def solve(self):
pass

def analyze(self):
pass

lin_eq = LinearEquation(2, 3)
print(lin_eq)
``````

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### Challenge Information:

Learn Interfaces by Building an Equation Solver - Step 24

and its because i haven’t concatenated it which is like “something” + " something else"

wait huh

``````equation_string = ' '.join(terms) + ' = 0'

``````

ive done it but how the hell is it wrong

i think its cuz of
Also, to refine the output, remove any leading `+` sign from `equation_string` .
but idk how do it without

Use the ‘strip’ method on the `equation_string`, in the line that includes the ‘return’ statement.
Read about this method here:

``````equation_string = ' '.join(terms) + ' = 0'
equation_string.strip('+')
return equation_string
``````

i’ve now got this, but it doesn’t work

never mind lol i was being dumb

Return `equation_string.strip('+')` literally. One line instead of two code lines:

``````        equation_string.strip('+')
return equation_string
``````
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yeah i know i done it, it was a dumb mistake

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