Answer :
Building and solving an equation to model the situation, it is found that he collected 78 pieces of candy on Hallowen night.
- Initially, he collected x pieces.
- Ate 7, thus [tex]x - 7[/tex].
- On the next day, eats 10%, and has 63 remaining, thus [tex]x - 7 - 0.1x = 63[/tex]
Solving for x, we find how many pieces of candy he collected, thus:
[tex]x - 7 - 0.1x = 63[/tex]
[tex]0.9x = 70[/tex]
[tex]x = \frac{70}{0.9}[/tex]
[tex]x = 77.8[/tex]
Rounding, he collected 78 pieces.
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