1: For any non-zero natural number x y, the symbol "△" is defined to represent an operation, and X △ y = 2XY of X + y, then 4 △ 5 is obtained 2: Three workshops produce a batch of parts. The first workshop produces a part, the second workshop produces the remaining 20% of the first workshop, and the third workshop produces 800, just finishing the task. How many parts are produced in the second and third workshop? 3: Ziqiang's savings are 30 yuan more than Jiahui's, and 3 / 4 of Jiahui's savings are 10 yuan less than 2 / 3 of Ziqiang's?

1: For any non-zero natural number x y, the symbol "△" is defined to represent an operation, and X △ y = 2XY of X + y, then 4 △ 5 is obtained 2: Three workshops produce a batch of parts. The first workshop produces a part, the second workshop produces the remaining 20% of the first workshop, and the third workshop produces 800, just finishing the task. How many parts are produced in the second and third workshop? 3: Ziqiang's savings are 30 yuan more than Jiahui's, and 3 / 4 of Jiahui's savings are 10 yuan less than 2 / 3 of Ziqiang's?

X △ y = 2XY of X + y,
4△5=2*4*5/(4+5)=40/9