First you find what is 7% of 39.99 by multiplying 39.99•0.07
39.99•0.07= 2.7993
Now because you are being taxed (MORE money) you add that amount to the original cost
2.7993+39.99=42. 7893
You are probably going to need to round it but I’ll leave it like that bc I don’t know if u need to round it to its nearest tenth, hundredth :)