Solving two math problems (3 minutes) 1. Given a = 2x2 power + 3xy-2x-1, B = - x2 power + XY-1, and 3a + 6B has nothing to do with X, find the value of Y (requires formula and answer) 2, three consecutive even numbers, the middle one is 2n, arrange the three numbers from small to large, and get a three digit number. When n is the value, the three digit value is the maximum, and find the maximum value. (formula Plus answer) fast, time limit is three minutes

Solving two math problems (3 minutes) 1. Given a = 2x2 power + 3xy-2x-1, B = - x2 power + XY-1, and 3a + 6B has nothing to do with X, find the value of Y (requires formula and answer) 2, three consecutive even numbers, the middle one is 2n, arrange the three numbers from small to large, and get a three digit number. When n is the value, the three digit value is the maximum, and find the maximum value. (formula Plus answer) fast, time limit is three minutes

two point four six eight
The three even numbers are 2n-2, 2n, 2n + 2
Then the three digits are (2n-2) * 100 + 2n * 10 + 2n + 2 = 182n-198
Because 2n + 2

A math problem, 3 minutes to solve
Xiaoming and Xiaohua run along the circular track. It takes 60 seconds for Xiaoming to run a circle and 80 seconds for Xiaohua to run a circle. They run from the same place in the opposite direction. When they meet, Xiaoming runs 50 meters more than Xiaohua. How many meters is a circle of this track?

1/60+1/80=7/240
（1/60-1/80）240/7=1/7
50*7=350

Three minutes!
In order to measure the distance between a and B at both ends of the pond, we designed the following scheme: 1
(I) as shown in Figure 1, take a point C on the flat ground that can directly reach a and B, connect AC and BC, and extend AC to D and BC to e respectively, so that DC = AC and EC = BC. Finally, measure the distance of De, that is, the length of ab;
(II) as shown in Figure 2, first make the vertical line BF of AB through point B, then take two points c and D on BF to make BC = CD, then make the vertical line of BD through D intersect the extension line of AC at e, then measure the length of De, which is the distance of ab
The purpose of BF ⊥ AB and ED ⊥ BF in scheme (II) is to___________ If only
Is scheme (II) Tenable__________ .
We must say why, what is the meaning of "if only ∠ abd = ∠ BDE = 90 °" in the title? This is not the same as vertical? Is the original BC = CD a condition

Scheme (II) is not necessarily true if ∠ abd = ∠ BDE is satisfied
A, C and D are not necessarily collinear
The results show that ACB is not necessarily congruent ECD and De is not necessarily equal to ab
Scheme (I) is feasible
∵∠ACB＝∠ECD,AC＝CD,BC＝CE
Scheme (I) is feasible
Scheme (II) is feasible
∵∠ACB＝∠ECD,∠ABD＝∠BDE,BC＝CD
Scheme (Ⅱ) is feasible

Detective Conan was walking by the sea when he overheard some pirates discussing how to divide the spoils
A pirate said, "if no one divides six pearls, there will be five left."
A pirate said, "if no one divides seven pearls, there will be eight less“
Conan has a few pearls and pirates. Do you know?

Suppose there are x pirates in total
The equation 6x + 5 = 7x-8 is obtained
The solution is x = 13
So pirate 13 pearls: 6 * 13 + 5 = 83