Question

Lin and Noah are solving the equation `7(x+2)=91`. Lin starts by using the distributive property. Noah starts by dividing each side by 7. Show what Lin's and Noah's full solution methods might look like.

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Answer 1

The solution is x=11

Explanation:

The original equation is

7(x+2)=91

Lin uses the distributive property, which states that

a (x+y) = ax + ay

By applying the property to this case,

7(x+2)=91

7x+14=91

Then we subtract 14 on both sides:

7x+14 - 14 = 91-14

7x=77

Finally, we divide by 7 on both sides:

7x÷7 = 77÷7

x=11

Noah starts by dividing each side by 7, so he gets:

7(x+2)÷7 = 91÷7

x+2= 13

Then he can subtract +2 from both sides:

x+2-2 =13 - 2

x=11

So, they get the same result. The similarity between the two methods is that they both divide by 7, while the difference is that Lin has to subtract 14, while Noah has to subtract 2.

Answer 2

Explanation:

Lin’s method

- multiply both x and 2 by 7

7x+14 = 91

- add -14 at both members

7x+14-14 = 91-14

7x = 77

- divide the two members by 7

x = 11

Noah’s method

- divide the two members by 7

x+2 = 13

- add -2 at both members

x+2-2 = 13-2

x = 11