Answer:
1. x+4x
2. 5x
3. 

4. 4x-2x+15
5. 

Explanation:
To write expressions remember these key words:
- a number is a variable like x
- sum is +
- difference and subtracted is -
- quotient is ÷
- product is ×
- reciprocal means flip like 
  
- square is an exponent of 2 like 
  
1. x+4x
2. 5x
3. 

Remember a quotient would be 
 but the reciprocal is
but the reciprocal is 
 .
.
4. 4x-2x+15
5. 
