Today’s problem — free all day, every step. Every day has one.
Seven photo frames — the area of EFGH
7 identical rectangular photo frames are mounted together to form a large rectangular display board EFGH for a school exhibition. 2 frames lie flat along the top and 5 frames stand upright below them, as shown. The perimeter of EFGH is 204 cm. Find the area of EFGH.
Show the answerHide the answer
See all 8 steps
MathBrush is being tested with a few parent groups, and every solution on the site is open to them — one household, all children. If you were given a code, it goes in once and this device remembers it.
I have a code → See a free one like it
65 worked examples are free without a code, two from every pattern. No account, either way.
The pattern behind it: Repeated identity
One length or count, described two ways in the same question.
In this one. Repeated identity: the width of the board is counted twice — as 2 lengths along the top and as 5 breadths along the bottom — and setting the two counts equal, 2L = 5B, fixes L : B = 5 : 2 without knowing either number.
How to spot it
A shape or count is described from two viewpoints in the same question, such as one edge measured as a number of long pieces and again as a number of short pieces.
Common mistake
Children treat the two descriptions as separate quantities and add them. Both describe the same quantity, so the two must be equal.
Try one like it
Standard Water — poured into a second container A rectangular tank measures 30 cm by 20 cm by 25 cm. It is 3/5 full of water. All the water is poured into a second rectangular co…The 33 problem patterns
All 33 patterns, one to a page — the 19 behind Primary 5 and 6 word problems, and the skills the younger years are built on. The bar model, how to spot it in the question, and the mistake children make. A booklet you can print. Free.
A PDF, and a note when new solutions go up.