Answer:
ST=6
Step-by-step explanation:
Since the question said they were approximate it means that the difference between every side's length is the amount added to the smaller one to get the bigger triangle. You find the difference (which is 2,by the way (7-5 or OC-OU)) of the given side's and relate their similarities (in this case we'll add, so it's the difference plus the other side). We've been given TU as 4 so ST=TU+2, ie. 4+2=ST
