SOLUTION: Is it B? I want to check my answer. Camille is saving for a laptop that costs about $850. To model her savings plan and determine how many more months it will take her to reach

Question 1174847: Is it B? I want to check my answer.
Camille is saving for a laptop that costs about $850. To model her savings plan and determine how many more months it will take her to reach her goal, she recently created this equation, where y represents the total amount saved and x represents the number of months. Which statement about her work is true?
The question is provided in the link here: https://i.imgur.com/YRMjv5R.png

A. Camille used the associative property in step 3.
B. Camille used the multiplication property of equality in step 4.
C. Camille used the subtraction property of equality in step 5.
D. Camille used the substitution property in step 6.
Answer by Theo(13342) (Show Source): You can put this solution on YOUR website!
here's a reference on the properties of equality.

https://www.varsitytutors.com/hotmath/hotmath_help/topics/properties-of-equality

it appears that the answer should be D.

in D, she replaced y with 850.

that's a substitution.

it is possible that B would also be considered because division is a form of multiplication, but that's not as clear as what happens in step 6.

for example:

step 4 says (y - 80) / 70 = 70x / 70

that's clearly a division, but it could also have been stated as:

(y - 80) * (1/70) = 70x * (1/70).

if stated that way, then the distributive property would also have to be implicated, because:

(y - 80) * (1/70) = y * 1/70 - 80 * 1/70.

i don't think they wanted the answer to be that complicated.

step 6 is more straight forward.

you are replacing y with 850 because y = 850.

that's a substitution.

you never really know what's in the minds of the people asking these questions, but i would go with step 6 because it's more clearly a substitution and the division property is stated separately from the multiplication property, even though they are two sides of the same coin.

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