Answer:
Error: Sariah treated every term as though it were an x-term. 5 and -4.5 are constants that cannot be combined with the x-terms. They can only be combined with each other.
Correct solution: 31x + 0.5
Strategy: Pay attention to the variables.
Step-by-step explanation:
In her first step, it appears Sariah added 13x and 5 to get 18x. These terms are not <em>like terms</em>, so cannot be added in this way. An appropriate strategy is to first identify all the terms with the same <em>variables</em> (x in this case), then add their <em>coefficients</em>.
... = x(13 +17 +1) +5 -4.5
Likewise, all the <em>constant</em> terms can be added.
... = 31x +(5 -4.5)
... = 31x + 0.5
