8 * $5 = $<<8*5=40>>40 is the price of 8 scissors.
10 * $4 = $<<10*4=40>>40 is the price of 10 erasers.
You can find the total price by adding the cost of the scissors and erasers: $40 + $40 = $<<40+40=80>>80
$100 - $80 = $<<100-80=20>>20 is the remaining amount of his money.
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