Answer:
89.44%.
Explanation:
Let's work out the probability he misses both throws:
Prob( he misses both throws) = (1-0.78) * ( 1 - 0.52)
= 0.22*0.48
= 0.1056.
So the probability he makes at least one free throw = 1 - 0.1056
= 0.8944.
(It is 1 - 0.1056 because the default of missing both throws is either making one throw on first or second attempt, or making both throws).