# Math Is Fun Forum

Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫  π  -¹ ² ³ °

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## #1 2024-04-25 05:48:02

Irene
Member
Registered: 2024-04-22
Posts: 34

### More questions.

1. A woman is four times as old as her son. In 5 years time, she will be three times as old as her son. How old is the woman?

I love Maths

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## #2 2024-04-25 05:50:22

Irene
Member
Registered: 2024-04-22
Posts: 34

### Re: More questions.

2. The sum of the interior angles of an octagon is equal to?

I love Maths

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## #3 2024-04-25 05:54:22

Irene
Member
Registered: 2024-04-22
Posts: 34

### Re: More questions.

3. Solve the simultaneous equations: 3b + 8a -1 =0 and 12-a+ 2b =0.

I love Maths

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## #4 2024-05-21 08:45:53

mathxyz
Member
From: Brooklyn, NY
Registered: 2024-02-24
Posts: 1,053

### Re: More questions.

Irene wrote:

2. The sum of the interior angles of an octagon is equal to?

Post your  math questions in the correct forum.

The sum of the interior angles of any polygon can be found using the formula: (n-2) • 180 degrees, where n is the number of sides or vertices in the polygon.

For an octagon, which has 8 sides, we can use this formula:
(8-2) • 180 = 6 * 180 = 1080 degrees.

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## #5 2024-05-21 08:51:23

mathxyz
Member
From: Brooklyn, NY
Registered: 2024-02-24
Posts: 1,053

### Re: More questions.

Irene wrote:

3. Solve the simultaneous equations: 3b + 8a -1 =0 and 12-a+ 2b =0.

Post your questions in the correct forum.

3b + 8a - 1 = 0...equation A

a + 2b = 0...equation B

Rewrite equation A this way: 8a + 3b = 1.

We now have:

8a + 3b = 1
a + 2b = 0

Solve equation B for a.

a + 2b = 0

a = - 2b

Plug -2b for a in equation A to find b.

Can you take it from here?

This is called the substitution method.

Last edited by mathxyz (2024-05-21 08:51:55)

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## #6 2024-05-21 08:56:15

mathxyz
Member
From: Brooklyn, NY
Registered: 2024-02-24
Posts: 1,053

### Re: More questions.

Irene wrote:

1. A woman is four times as old as her son. In 5 years time, she will be three times as old as her son. How old is the woman?

Post your questions in the right forum.

Woman = 4x

Son = x

Woman in 5 years = 4x + 5.

Son in 5 years = x + 5.

4x + 5 = 3(x + 4)

Solving for x I get 10.

The Son is 10 years old.

The woman is 4(10) or 40 years old.

As you know, 40 is three times greater than 10.

Woman is 40.

Son is 10.

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## #7 2024-05-21 22:00:52

Irene
Member
Registered: 2024-04-22
Posts: 34

### Re: More questions.

Thanks and okay i will post them in the right forum next time.

I love Maths

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## #8 2024-05-22 08:43:53

mathxyz
Member
From: Brooklyn, NY
Registered: 2024-02-24
Posts: 1,053

### Re: More questions.

Irene wrote:

Thanks and okay i will post them in the right forum next time.

No problem. Thanks.

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