Answer:
Josh's total bill is $ 27.825
Explanation:
Given:
The subtotal of the Josh Bill = $21.00
Finding the usual amount Josh gave as Tip To his sever:
Usually josh tips 20% to all servers
So Tip = 20% of his subtotal
=>

=>

=>

=>4.2
So Josh usually tips $4.2 to his server
Finding the amount Josh gave 25% as Tip To his sever:
But now he tips 25% which is
=> 25% of 21
=>

=>

=> 5.25
Thus the tip amount will be $5.25
So he will be giving (5.25 - 4.2) = $1.05 more than the usual tip
Finding the total bill
The total bill = subtotal+ 7.5% sales tax + 25% tip
=> 21 + 7.5 % of 21 + 25% of 21
=>

=>

=> 21 +1.575 +5.25
=>27.825