Answer:
See below
Explanation:
13x + 5 + 17x - 4.5 + x
NOTE: You can only add/subtract LIKE terms . Here we have variable terms in x (13x , 17x and x) and 2 constants ( 5 and 4.5).
Sarah's next line is
18x + 17x - 4.5 + x
This is incorrect . It looks like she added 13x + 5 and got 18x!! Which is of course wrong because they are NOT LIKE terms. 5 is a constant and 13x is a variable term in x.
The third line is correct:-
35x - 4.5 + x.
She has added the 2 variables 17x and 18x.
Fourth line is 30.5x + x. She's at it again - Trying to subtract 4.5 from 35x .
Last line 31.5x
She has added the 2 terms in x correctly, but the final answer is wrong of course due to the earlier errors.