Could you help giving me explanations on the following problem ? Thank you. Financial Math

Liability payments of 100 each are due to be paid in 2,4 and 6 years from now. Asset cashflow consists ofA1=71.45 in 1 year andA5=229.41in 5 years. The yield for all payments is 10%. An attempt is made to have the asset cash flow immunize the liability cashflow by matching present value and duration.

(b) Showed Redington immunization are satisfied.

I have the explanation from textbook but I don't understand, please explain more based on the explanation from textbook shown below.