Unable to find expansion in regular perturbation problem

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Consider the equation: $\varepsilon^{3}x+x=1$.

  1. Look for a rescaling of this equation in the form $x = \varepsilon^n X$ with $X \in O(1)$ and explain what value $n$ should take to find two more solutions.

I've plugged in the substitution into the original equation to get:

$$ \varepsilon^{n+3}X + \varepsilon^{n}X = 1 $$

but I don't know how to explain a value for $n$ that will yield two more solutions.

What am I supposed to be looking for here?

I would be very grateful if someone is able to point me in the right direction.