Answer:
Step 5
Step-by-step explanation:
The mistake is in step 5.
The previous step was
[tex]step \: 4 : 2 + 10 \div 2[/tex]
The order operations, PEDMAS, must be applied:
We have Addition and Division here,
Using PEDMAS, we must divide first to get:
[tex]step \: 5 : 2 + 5[/tex]
We can now add to get:
[tex]step \: 6: 7[/tex]
Therefore the mistake occurred at step 5
