The answer would be 15. The average of 6, 7, 8, 9, and 15 is 9. Hope this helps.
<span>7^2•3^2+(1+2)^0•3-4^2•1
= 49</span>•9 + 1•3 - 16<span>•1
= 441 + 3 - 16
= 428</span>
The best answer among the choices provided by the question is $1200 in the first month, $1285.48 in the second month, $1370.96 in the third month .