Answer: The required number that Frank is thinking of is 7.
Step-by-step explanation: Given that Frank is thinking of a number between 1 and 10 such that if he multiply the number by 8 and add 3, he get 59.
We are to find the number that Frank is thinking of.
Let x represents the number that Frank is thinking of.
Then, according to the given information, we have

Thus, the required number that Frank is thinking of is 7.