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=
![0.2*21=4.2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/qv65eat2wgcyd6hyp3xss57gd7t2kquigq.png)
Current tip= 25% of 21=
![0.25*21=5.25](https://img.qammunity.org/2020/formulas/mathematics/middle-school/5bngvap1g7f6fya7qogdzzsvpkwgnek05n.png)
Josh tips to his server = $5.25
Increase in tip=
![5.25-4.2 =\$1.05](https://img.qammunity.org/2020/formulas/mathematics/middle-school/mfvvvb2jnq1k0ial9tytxowcmc3macn28i.png)
So, he tips $1.05 his server today, than he normally would tip.
Now, Tax amount =7.5 % of 21=
![0.75*21=\$15.75](https://img.qammunity.org/2020/formulas/mathematics/middle-school/pw89mofxfrx0ybyhl7gifjtum1f1bfoxya.png)
Hence, Josh final bill= Subtotal before tax+tip+tax
![\$21+\$5.25+\$15.75=\$42](https://img.qammunity.org/2020/formulas/mathematics/middle-school/mbas366t7t5kvd4642vvhw0sgitwpx1r9r.png)