<span>8 + 5n = -72
5n = -72 - 8
5n = - 80
n = -80/5
n = -16</span>
The sum of three primes is 18 so they must all be smaller than 18 as well.
Primes less than 18=2,3,5,7,11,13,17
2,3, and 13
2,5, and 11
There are two solutions...
Answer: F=bill for first shop=4S-$630; S=bill for second shop
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F+S=$3265 Substitute for F
4S-$630+S=$3265
5S=$3895
S=$779 ANSWER 1: The bill for the second shop was $779
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F=4S-$630
F=4($779)-$630
F=$3116-$630=$2486 ANSWER 2: The bill for the first shop was $2486.
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CHECK:
F+S=$3265
$2486+$779=$3265
$3265=$3265
explanation: