# 4x + 6 = 8 what is x? Your age when your father is twice as old as you? How's the formula? 143 views
In 7-9
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## 2 lessons

by Guru (6.1k)
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Linear equation

Quite often in life, we know some variables, but we must figure out an unknown. For example, we may want to save money for a moped, but to know how long it is going to take, we must be able to calculate it according to our weekly allowance, price of the moped and perhaps other things we are going to end up buying with the money.

Practical example:

How long would it take for you to come up with the money if your weekly allowance was 10€, the price of the moped 1550€ and you would buy sweets with 2€ every week? What kind of calculations do you need to make to get the answer?

Equations are a way of writing expressions with unknown variables that can be figured out using math.

Let’s learn the theory:

Excercises:

1. Figure out the X

• x/9 = 1/3
• 20/x = 5/1
• x/12 = 2/3
• 6/16 = 3/x
• x/4 = 5/20
• 3/8 = x/24

2. A runner’s step is such that on a 100m distance he takes 83 of them. How many steps must he take to run 1,7km? Come up with the equation and solve the X.

3. Solve the equation by dividing both sides with the same number.

• 3x = 60
• 10x = -30
• -2x = 24
• -5x = -30

4. Solve the equation by multiplying both sides with the same number.

• x/3 = 4
• x/3 = -7
• x/-9 = 4

5. Solve the equation.

• x/3 = 500
• x + 9 = 13
• 12x = 11x + 3