At a restaurant there is 7% sales tax. if the bill was $8.64, how much would he be owed in total?

Ok, so in order to get tax on something you multiply the amount by the amount of tax in decimal form and then add back the original amount. So for this, you'd start with 8.64*0.07, which equals 0.6048. This rounds to 0.60. 8.64+0.60=9.24

So, he would owe $9.24 total.