Okay, let's find out how much the tax was by finding out what 7% of $28 is, we do this by multiplying:
[tex]\sf 28\cdot 7\%[/tex]
Convert 7% into a decimal, we do this by dividing it by 100 because percentages are parts of 100:
[tex]\sf 28\cdot 0.07[/tex]
Multiply:
[tex]\sf 1.96[/tex]
So this is the tax. Add it to the original price to get the total price:
[tex]\sf 28+1.96=\boxed{\sf \$ 29.96}[/tex]