Posted by Chelsea on .
Every item in the Just a Dollar store is priced at $1.00. When Mary Jo opens the store, there is $128.50 in the cash register. When she counts the money in the cash register at the end of the day, the total is $1023.10. If the sales tax rate is 6.5%, how many items were sold that day?
Can someone please help me with this problem. I never know how to set these problems up.

Algebra 
Damon,
n items
each costs 1+.065 = 1.065
so
1.065 n = 1023.10  128.50 
Algebra 
Ms. Sue,
1023.10  128.50 = 894.6
894.6 / 1.065 = 840 
Algebra 
Chelsea,
Thank You both!!
I have another question that is similar to this one..
An accountant earns $3180 per month after receiving a 8.5% raise. What was the accountant's monthly income before the raise? Round your answer to the nearest cent.
What i thought you did was 3180*8.5%=270.3
3180270.30=2909.70, but it says its not correct. Any ideas on how to do this?