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Area of the overlap?

A normal-level "Area" problem."Sum of the sheets − what you see = the overlap." It works even when you know nothing about the overlap's shape or position.

GivenA 8 × 6 cm sheet and a 10 × 5 cm sheet overlap; the whole shape measures 83 cm²

Area ★★★☆☆☆ Area of the overlap? 6cm 8cm 5cm 10cm

Hints

  1. The overlap's dimensions are not given, so go the long way round. The first sheet is 8 × 6 = 48 cm².
  2. The second is 10 × 5 = 50 cm². Spread flat without overlapping, the two sheets come to 98 cm².
  3. But the shape you actually see measures only 83 cm². Why is it smaller than 98?
  4. The cause is the overlap. Both sheets cover it, so the sum counted it twice — while the shape you see contains it only once.
  5. The gap between "counted twice" and "counted once" is exactly the extra copy — the overlap. 98 − 83

Answer 15cm²

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