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<span>n = 11<span>.
Explanation:
Let m be the number of boxes Mark sells and a be the number of boxes Ann sells.
Since Mark sells 10 less than n, m = n-10. Since Ann sells 2 less than n, a = n-2.
Together, they sold n-10+n-2=2n-12 boxes.
We know that they sold less than n boxes, so our inequality would be
2n-12<n.
To solve this, subtract n from both sides:
2n-12-n<n-n; n-12<0.
Add 12 to both sides:
n-12+12<0+12; n<12.
This means there were less than 12 boxes. The next number down is 11; this woks because Mark sold 10 less than n; 11-10=1. Mark sold at least 1 box.
If n=10, however, 10-10=0; this doesn't work, because Mark did sell at least 1 box. </span></span>
121.50 divided by 9 is 13.50. 13.50 times 5 equals 67.50
