Answer:
After substituting the first step is to open the bracket of middle term
Step-by-step explanation:
Given the equation
[tex]x+3x-4.2[/tex]
when x=5, we have to determine the first step after substitution.
[tex]5+3(5)-4.2[/tex]
The first step is to open the bracket of middle term
[tex]5+15-4.2[/tex]
Then next step is to adding first two terms by BODMAS rule
[tex]20-4.2[/tex]
Now subtraction, we get 15.8