Okay heres all the questions i don't understand.
3y+5y/3=8
4c+6+2c=24
2x/5-3/5=11/5
2/5b-1/4b=3
15-6g+8=19
w/4-w/5-1/3=16/15

Multiply 3 to both sides:

3y + 5y = 24

Combine like terms:

8y = 24

Divide 8 to both sides:

y = 3

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4c + 6 + 2c = 24

Combine like terms:

6c + 6 = 24

Subtract 6 to both sides:

6c = 18

Divide 6 to both sides:

c = 3

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2x/5 - 3/5 = 11/5

Add 3/5 to both sides:

2x/5 = 14/5

Multiply 5 to both sides:

2x = 14

Divide 2 to both sides:

x = 7

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2/5b - 1/4b = 3

Combine like terms:

3/20b = 3

Divide 3/20 to both sides or multiply by its reciprocal, 20/3:

b = 20

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15 - 6g + 8 = 19

Combine like terms:

23 - 6g = 19

Subtract 23 to both sides:

-6g = -4

Divide -6 to both sides:

g = -4/-6

Simplify:

g = 2/3

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w/4 - w/5 - 1/3 = 16/15

Change w/4 and -w/5 into fractions with like denominators:

5w/20 - 4w/20 - 1/3 = 16/15

Combine like terms:

w/20 - 1/3 = 16/15

Add 1/3 to both sides:

w/20 = 21/15

Multiply 20 to both sides:

w = 28

2160ft^3 i think you could use a formala to you out with this in the future