Why does my child think 2x + 4 = 10 becomes 2x = 14?
Your child moves a number across the equals sign without changing its sign.
Why children do it
Many children are taught to move a number to the other side and change its sign. It's a shortcut for taking 4 from both sides, and once the reason is forgotten, the sign change goes too. Saying "take 4 from both sides" keeps the reason in view: 2x = 6.
How to help at home
Instead of moving a number across the equals sign, do the opposite to both sides, and say it out loud: "take 4 from both sides".
The right way
Solve: 5x + 3 = 2x + 15
- 3x + 3 = 15Subtract 2x from both sides.
- 3x = 12Subtract 3 from both sides.
- x = 4Divide both sides by 3.
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