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3 years ago

If m + n = 7 and 2n - 3m = 6, what is the value of 3n - 2m ?

2 answers:

8 0

Since m + n = 7 we know m = 7-n. So now we have 2n - 3(7-n) = 6. From this we get n = -3. So now we know m - 3 = 7 so m = 10. So now we have 3(-3) + 2(10) = ? and this comes out as 11

Veronika [31]3 years ago

7 0

<span>m + n = 7 then m = 7 - n
2n - 3m = 6
</span><span>
substitute </span>m = 7 - n into 2n - 3m = 6
2n - 3m = 6
2n - 3(7 - n) = 6
<span>2n - 21 + 3n = 6
5n - 21 = 6
5n = 27
n = 27/5
n = 5.4

</span><span>m + n = 7
</span><span>m = 7 - n
m = 7 - 5.4
m = 1.6

now you have m = 1.6 and n = 5.4
you can find the value of </span>3n - 2m<span>

</span>3n - 2m
=3(5.4) - 2(1.6)
= 16.2 - 3.2
= 13

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<h3><u>Answer:</u></h3>

<h3><u>Step-by-step explanation:</u></h3>

let's rewrite this

x + y = 11 <em>- equation 1</em>

- x = - y - 9 <em>- equation 2</em>

solve the first equation for x

x + y = 11 (add -y to both sides to get x by itself)

x = -y + 11 <em> - equation 3</em>

now substitute -y + 11 for x in the second equation

y - 11 = - y - 9 (2 negative signs next to each other equals positive)

2y - 11 = -9 (add y to both sides)

2y = 2 (add 11 to both sides)

y = 1 (divide both sides by 2)

now substitute y = 1 into equation 3

x = -1 + 11

x = 10

therefore, x = 10 and y = 1. in coordinates, x goes before y

therefore, the coordinates are (10, 1)

therefore the answer is D

good luck my friend! hope this helped a lot! also, i found a website if you don't fully understand this, its called MathPapa, i didn't use it to work this out so my working might be different but it definitely helps me sometimes. for an equation like this, type it likes this: x+y=11; -x=-y-9

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<h3>Given information-</h3>

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