Answer: Josh tips to his server = $5.25
He tips $1.05 his server today, than he normally would tip.
Josh final bill=$42
Explanation:
Given: Josh subtotal amount before tax = $21.00
Previous tip =20% of 21=

Current tip= 25% of 21=

Josh tips to his server = $5.25
Increase in tip=

So, he tips $1.05 his server today, than he normally would tip.
Now, Tax amount =7.5 % of 21=

Hence, Josh final bill= Subtotal before tax+tip+tax
