Answer:
The coefficient of 
 is 10.
Explanation:
Given : Expression 

To find : Simplify and determine the coefficient of expression ?
Solution : 
Expression 

Simplifying the expression by multiplying,

Multiplying two negative number gave positive number.
Coefficient is defined as the number multiply by a variable or term.
In 

The coefficient is 10.
Therefore, The coefficient of 
 is 10.