One-step equations

Discover

A balance has $x$ and 4 weights on one side and 11 weights on the other. What is $x$ ?

Key idea

Undo the operation on both sides.

An equation stays true if you do the same to both sides. Undo adding by subtracting, subtracting by adding, multiplying by dividing, dividing by multiplying.

Worked example

$5x = 35$ and $x - 8 = 12$ .

x = 7

Divide by 5.

x = 20

Add 8.

Your turn, guided

Your turn: $x + 9 = 23$ .

14

23 − 9.

Practice ★

Solve $x + 10 = 37$ . $x = \;?$
Solve $x + 23 = 35$ . $x = \;?$

Solve $11x = 77$ . $x = \;?$

Watch out!

Practice ★★

Solve $\dfrac{x}{ 3 } = 7$ . $x = \;?$
Solve $\dfrac{x}{ 3 } = 6$ . $x = \;?$

Exit ticket

Three questions to check you have got it.

Solve $x + 10 = 37$ . $x = \;?$
Solve $x + 23 = 35$ . $x = \;?$
Solve $x + 27 = 59$ . $x = \;?$

Summary card

One-step equations

Do the opposite operation to both sides.

Watch out: undo × with ÷ and ÷ with ×.

End of the lesson

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