Suppose the output of the first farmland was X kg last year, and the output of the second farmland was Y kg.

Then according to the meaning of the question: "Last year's output was 320kg", it can be concluded that: x+y=320.

(formula1);

"The output of the first agriculture is 80% lower than last year, and the output of the second agriculture is 90% lower than last year."

Available: 0.2x+0. 1y=35.

(2);

Simultaneous (1), (2) x=30, y=290, then 0.2x = 6,0.1y = 29,

Therefore, the peanut output of this farmer's two plots this year is 6 kg and 29 kg respectively.