Given:
Daniel bought a bicycle for $80 and a helmet for $20.
Sales tax = 5%
To find:
The total amount of both items including tax.
Solution:
Price of bicycle (excluding tax)=

Price of helmet(excluding tax) =

Price of both items =

=

Now, the sales tax is 5%. So,
Price of both items (including tax) =

=

=

Therefore, the Daniel pays $105 for the two items, including tax.