Why does my child solve x/3 + 4 = 9 as x = 27?
Your child multiplies without first undoing the number added or taken away.
Why children do it
x was divided by 3, then had 4 added. Undoing goes in reverse order, last thing first: take away the 4, then multiply by 3. Children who multiply straight away forget the 4 altogether. x/3 + 4 = 9 means x/3 = 5, so x = 15.
How to help at home
Undo things in reverse order: first the number added or taken away, then the division.
The right way
Solve: x/3 + 4 = 9
- x/3 = 5Subtract 4 from both sides.
- x = 15Multiply both sides by 3.
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