Answer:

Step-by-step explanation:
Let
denotes number of pencils, markers, erasers respectively.
For Andrea:

For Justin:

For Virginia:

On subtracting equations (i) and (ii), we get

Put
in equation (i)

Put
in equation (iii)

Multiply equation (iv) by 5 and equation (v) by 6 and then subtract both the equations.

Put
in equation 

Put
in equation (i)

Answer:
<h2><em><u>
A to C = 25
</u></em></h2><h2><em><u>
A to B = 13
</u></em></h2><h2><em><u>
C to B = 37
</u></em></h2><h2><em><u>
</u></em></h2>
Step-by-Step Explanation:
<em><u>Perimeter</u></em> = 75
<em><u>Sides:</u></em>
2x + 3
3x + 4
2x - 9
<h2 /><h2><em><u>
1. Equal the sides added together to the perimeter</u></em></h2>
75 = 2x + 3 + 3x + 4 + 2x - 9
<h2><em><u>
2. Simplify Like terms</u></em></h2>
2x + 3 + 3x + 4 + 2x - 9 = 7x - 2
<h2><em><u>
3. Place the equation back together</u></em></h2>
75 = 7x - 2
<h2><em><u>
4. Isolate the variables and numbers</u></em></h2>
75 = 7x - 2
+2 +2
77 = 7x
<h2><em><u>
5. Simplify the equation</u></em></h2>
77 = 7x
/7 /7
<h2><em><u>
11 = x
</u></em></h2>
<h2><em><u>
6. Substitute the value of x into the side lengths.</u></em></h2>
2x + 3 = 2(11) + 3 = 22 + 3 = <em><u>25</u></em>
3x + 4 = 3(11) + 4 = 33 + 4 = <em><u>37</u></em>
2x - 9 = 2(11) - 9 = 22 - 9 = <em><u>13</u></em>
Answer:X=5/6 Y=8/5
Step-by-step explanation:
-6x +5y=3
+6x
5y=6x+3 (divide each number by 5)
Y=6/5x + 3/5 (Plug that into your x equation)
12x+15 (6/5x + 3/5) =34
(Multiply 15 by the numbers in the brackets you can break it down and do 15•6 divided by 5 )
15•6=90 divided by 5=18x
15•3= 45 divided by 5=9
(Add like variables)
12x+18x=30x
30x+9=34
(Subtract 9 from itself do the same to 34)
9-9= 0
34-9=25
Divide 30 by itself to get x by itself then divide 25 by 30
25 divided by 30= 5/6
X=5/6 (plug that into the y equation)
Y=6/5•5/6+3/5
Multiply 6/5 and 5/6 straight across because this is multiplication you don't need like denominators
6/5•5/6=30/30=1
Y=1+3/5
1/1 + 3/5
Here you need to have like denominators because it is addition so just use 5
5•1=5
5/5+3/5=8/5
Y=8/5
Answer:
a:c = 35:24
a:c = 20:27
a:c = 35:22
a:c = 28:27
Step-by-step explanation:
a:b = 7:3
Using cross products
3a = 7b
Divide by 7
3a/7 = b
Now we want
8b = 5c
Substitute in 3a/7 for b
8 (3a/7) = 5c
24/7a = 5c
Multiply by 7
24/7a *7 = 5*7c
24a = 35c
Divide by c
24 a/c = 35
Divide by 24
a/c = 35/24
a:c = 35:24
a:b = 4:9
Using cross products
9a = 4b
Divide by 4
9a/4 = b
Now we want
3b = 5c
Substitute in 9a/4 for b
3 (9a/4) = 5c
27/4a = 5c
Multiply by 4
27/4a *4 = 5*4c
27a = 20c
Divide by c
27 a/c = 20
Divide by 27
a/c = 20/27
a:c = 20:27
b:c = 5:11
Using cross products
11b = 5c
Divide by 11
b = 5c/11
Now we want
2a = 7b
Substitute in 5c/11 for b
2a = 7(5c/11)
2a = 35c/11
Multiply by 11
2a*11 = 35c
22a = 35c
Divide by c
22 a/c = 35
Divide by 22
a/c = 35/22
a:c = 35:22
b:c = 14:3
Using cross products
3b = 14c
Divide by 3
b = 14c/3
Now we want
9a = 2b
Substitute in 14c/3 for b
9a = 2(14c/3)
9a = 28c/3
Multiply by 3
9a*3 = 28c
27a = 28c
Divide by c
27 a/c = 28
Divide by 27
a/c = 28/27
a:c = 28:27