Answer:
First "order of operations" mistake: step 2
First arithmetic mistake: step 4
Step-by-step explanation:
As we understand Rena's work, she wants to simplify ...

for x = -1 and y = 2.
Her work seems to be ...
<u>Step 1</u>

<u>Step 2</u>

<u>Step 3</u>

<u>Step 4</u>

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So, the first arithmetic error is in Step 4. However, the order of operations requires exponents be evaluated first. Doing that makes step 2 look like ...

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We expect your answer is supposed to be Step 4.
Answer:
Delta Ft = 70*3 - 42*7 = 168 #$
1 cup and 2/4 is what she meeds to make 1 batch