# Algebra

Gustavs father is seven times as olda s he is.a. Year ago,he was nine timesa s olda s gustav. Find gustavs present age

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1. g = Gustavs age

f = Fathers age

Gustavs father is 7 times as olda s he is.

f = 7 g

Year ago,he was nine timesa s olda s gustav

( f - 1 ) / ( g - 1 ) = 9

( 7 g - 1 ) / ( g - 1 ) = 9 Multiply both sides by ( g - 1 )

7 g - 1 = 9 ( g - 1 )

7 g - 1 = 9 g - 9 Subtract 7 g to both sides

7 g - 1 - 7 g = 9 g - 9 - 7 g

- 1 = 2 g - 9 Add 9 to both sides

- 1 + 9 = 2 g - 9 + 9

8 = 2 g Divide both sides by 2

4 = g

g = 4

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2. f = father
g = Gustav

Write two equations.

f = 7g
f - 1 = 9(g - 1)

Substitute first equation into second.

7g - 1 = 9g - 9
7g - 9g -1 + 1 = 9g - 9g - 9 + 1
-2g = -8
-2g/-2 = -8/-2
g = 4

Substitute g value in either equation.

f = 7(4)
f = 28

Check:

One year ago.....
f is 27 and 9 times older than g
g is 3

27 = 3 * 9

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posted by Chelle
3. Gustav -- x
his father -- 7x

One year ago:
Gustav -- x-1
his father -- 7x-1

7x-1 = 9(x-1)
7x-1 = 9x - 9
-2x = -8
x = 4

Gustav is now 4 years old

check:
his father is now 28
one year ago, Gustav was 3 and his father would have been 27, which is 9 time Gustav's age

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posted by Reiny
4. If 22.5 L of nitrogen at 748 mm Hg are composed of 725 mm Hg at constant. What is yhe new volume?

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