Answer: Kelli's height= 3/4 x 
Explanation:
Hi, to answer this question we have to write an equation with the information given: 
- Kelli's height: 3/4 times her brother ted 
- Ted's height: x 
So, to obtain Kelli's height we simply have to multiply Ted's height (x) by 3/4 . 
Mathematically speaking: 
Kelli's height= 3/4 x 
Feel free to ask for more if needed or if you did not understand something.