7th grade math Ms. Sue help please thanks
posted by Delilah on .
11.
The sales tax rate is 6.9%.
a. Find the tax paid for a pair of boots with a list price of $128.
b. What is the total cost of the pair of boots? (1 point)
$8.83; $128.88
$8.83; $136.83
$0.88; $136.83
$0.88; $128.88
12.
Doug is a salesperson in a retail store and earns $75 per week, plus 15% of his weekly sales. If Doug makes $555 one week, what are his sales for that week? (1 point)
$3,200
$627
$566
$1,914
13.
Last year, a poll of 1,000 voters conducted by the staff of Senator Chun found that 522 people approved of the job the senator was doing. This year, a new poll of 1,000 voters shows that 423 people approve of the senator’s performance. Find the percent of change in the number of voters who approve of the senator’s performance, and identify it as an increase or decrease. (1 point)
19%; increase
23.4%; decrease
23.4%; increase
19%; decrease
14.
The owner of an audio store received a shipment of portable stereos at a cost of $102.30 each. If he sells the stereos for $181.99 each, what is the percent of markup? Round to the nearest whole percent. (1 point)
8%
44%
78%
80%
15.
In Store A, a book that regularly sells for $24.99 is on sale at 15% off. In Store B, the same book regularly sells for $27.99 and is on sale at 25% off. Which store sells the book for the lower sale price? (1 point)
Store A; Store A’s sale price is $18.74, and Store B’s sale price is $23.79.
Store A; Store A’s sale price is $18.74, and Store B’s sale price is $20.99.
Store B; Store A’s sale price is $21.24, and Store B’s sale price is $20.99.
Store B; Store A’s sale price is $21.24, and Store B’s sale price is $23.79.
16.
Find the final balance in an account with $730 invested at 3% annual simple interest for 4 years. (1 point)
$735.48
$87.60
$817.60
$8,760.00
My answers:
11. $8.83; $136.83
12. $3,200
13. 19%; decrease
14. 78%
15. ????????
16. $87.60
Thanks for checking! I don't know how to solve #15, so can you just give a little help? Thanks so much!

11) correct
12) correct
13) correct
14) correct
15) if it is 15% off ,then the sale price is 100 15 or 85%
If it is 25% off, the sale price is 75%
16) your are asking for the FINAL balance not finding the interest 
A store purchases a tshirt for 8.10. The store marks up the price by 90%. What is the retail price of the tshirt ? Helpp?