# Simple Arithmetic

Level pending

How may solutions are there so that $a + b + c + d + e = 20$ where $$a, b, c, d, e > -1$$ ?

For example,
$$a + b = 3$$ have 4 solutions :
$$a = 0, b = 3$$
$$a = 1, b = 2$$
$$a = 2, b = 1$$
$$a = 3, b = 0$$

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