Impress your friends with this cool mathematics puzzle. (and know how maths is useful in real life)

This lets you give the age of a person and the number of siblings in their family.

#### Questions that you need to ask

- Think of your age in years
- Multiply your age by 2
- Add 10
- Multiply by 5
- Add number of siblings that you have
- Subtract 50 from this number
- What's the number?

#### How it Works

## Question Answer Example Algebraic Equivalent

1. Think of your age in years 15 [10x+y]

2. Multiply your age by 2 30 2[10x+y]

3. Add 10 40 2[10x+y] + 10

4. Multiply by 5 200 5{2[10x+y]+10}=100x+10y+50

5. Add # of siblings you have 203 100x+10y+50+z

6. Subtract 50 153 [100x+10y+50+z]–50= 100x+10y+z

#### Prediction:

You are 15 years old, and you have 3 siblings.

The first two digits on the left (15) give your age, and the rightmost digit (3) gives the number of siblings you have.

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