This leads to:

Interest tax = principal × interest rate× time× 20%

It can also be said that interest tax = earning interest ÷80%×20%.

Generally, 20% of the interest will be deducted if the tax is deducted! If it is given in the title, it is used in the title. Generally, the title is tax-free ~ ~ ~

Formula solution: interest = principal × interest rate × time (tax-free)

So: principal = interest/interest rate/time.

Interest tax, that is, using principal × interest rate × time ×20%.

Example ② Calculation method:

Principal:1152 ÷ 3.20% ÷ 3 =12000 yuan.

Interest tax: 1 152÷80%×20%=288 yuan.

I hope it is helpful to you ~ ~ ~ Thank you for your adoption!