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1. First we looked at E and O because they had the same area but £110 price difference and E had 2 extra bits of frame. £110 extra divided by two bits of frame = £55 per cm of frame.

2. Then we measured A which was 28cm x £55 for the frame. We knew E or O was not correct because they had the wrong price for frame.

3. Then we looked at I and K with a £60 price difference and only 3 more cm of frame so each cm of frame was £20.

4. Then we measured the perimeter of H which was 8 x £20 = £160 and 3 bits of window for £30 pounds so £10 per each cm ².

5. Then we checked O and it was correct so we knew E was wrong because the real price is £460.