To solve this, you would first add the amount of the 3 checks they wrote together. So, 74+132+48=254. Then, we know that they had $317 in their checking account. Now, you would take the amount they had in their account (317), and subtract it by the total of the 3 checks they wrote (254).
The checking account balance is 317-254=63, so $63 is their checking account balance.
I really hope this helps you.