Question P4–P5–P6 Constant total
Ali had 3 times as many marbles as Ben. After Ali gave 24 marbles to Ben, the two boys had the same number of marbles. How many marbles did Ali have at first?
Money moves between two people, so their total never changes.
In this one. A transfer (unlike spending) leaves the total unchanged, so "equal after" just means re-splitting that same total of units evenly — and comparing how many units one side gained or lost tells you what a single unit is worth.
One person gives, sells or loses an amount to the other, and nobody outside the two people gains or loses anything.
Children draw different totals before and after, or forget that moving an amount from one person to the other changes the gap between them by twice that amount.
Worked examples of all 33 patterns and skills, in a booklet you can print.