Question

A television costs $350 before sales tax is applied. The final cost of the television was $378.

Answer 1

To get the answer we can use proportion. We know that 350 its 100% and 378 its 100% + taxes.
350% ------------ 100
378% ------------ x
cross multiply now
350*x=378*100
350x=37800      /:350
x=108 
Now we see that taxes its 8%, because final price its 100% + taxes = 108%