#Learn mathematics;Can you solve this tricky puzzle;#Puzzle#Reasoning

Mathematical Reasoning

Determine the missing value in the puzzle below :

Directions : In the following questions, four alternatives are given for the Idiom/Phrase printed in bold in the sentence. Choose the alternative which best expresses the meaning of the Idiom/ Phrase. You have been trying to solve this puzzle for a long time, be careful so that you avoid barking up the wrong tree

A can solve 75% of the problems in a book on mathematics and B can solve 70%. What is the probability that a problem chosen at random is solved?