Answer:
1.Javier did not write the coefficient raised to power of 3
2.Javier wrote
instead of 
3.Javier did divide exponents instead of subtraction of exponents
Step-by-step explanation:
We are given that Javier simplified the expression

We have to find three mistakes made by Javier.



By using property;
By using property:


By using property

Javier made three mistakes are given below:
1.Javier did not write the coefficient raised to power of 3
2.Javier wrote
instead of
3.Javier did divide exponents instead of subtraction of exponents.