1, apple 24x, pear 18x, apple sold 1/6, leaving 20x, pear is 18x-4. This is 5:4, 80x=90x-20 x=2.

Then there are 48 apples and 36 pears.

2. Let the conductor be 65,438+000 x meters, leaving 62.5x meters after the first use and 62.5x-27 meters after the second use. The line used is 37.5x+27. Equation shows that x is 1.2, and the whole plant is120m.

3. They brought 6x and 5x, and used 7y and 5y, so when 1 1x- 12y = 8, x is an integer of 1 1, that is to say, Naughty brought 66 yuan and smiled at 55 yuan, Naughty spent 56 yuan and smiled.

4, Bai Zi 75x, sunspot 100x, 9 1, one black, 0.625a white, 1.625a=9 1, indicating that there are 56 black and 35 white. The ratio of 75x-35 to 100x-56 is 4:3. Then, x=0.68 can be obtained. Then there are 5 1 albino stars and 68 sunspots.

5. The number of high school students is X, and the number of middle school students is 2x. High school boys 5y, girls 7y, junior high school boys 3z, girls 2z. 12y=x, 5z=2x. That is, y =112xz = 0.4x, and the ratios of 5y+3z and 7y+2z are obtained. Easy to get equal to 97:83