# Bomb The Target! Part 2

A B-2 spirit bomber is bombing a city. The chance that a bomb dropped by it hits the target is $$50$$%.

It requires $$2$$ direct and consecutive bomb hits to destroy the city. If the bomber drops 7 bombs, then the probability that the city isn't destroyed is $$\dfrac{a}{b}$$ where $$a$$ and $$b$$ are co-prime positive integers.

Find $$a+b$$.

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