Sierra simplified an expression as shown below: Given: x + 8 + 5(x - 4) Step 1: x + 8 + 5x - 20 Step 2: 5x + 8 - 20 Step 3: 5x - 12 In which step did Sierra make a mistake? What should she have done instead?

In which step did Sierra make a mistake? Step 2.

What should she have done instead? add the x and the 5x

Step-by-step explanation:

she had the expression:

and then she multiplied the 5 by the parentheses (step 1):

no mistakes so far

then she has:  (step 2) Here is the mistake, she forgot about the 'x' that she has at the beginning of the expression.

What you should have done is add the x and the 5x, so she must a 6x in the following step (correcting the mistake):

which gives us:

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step-by-step explanation: