There are 140 red and black balls in total. Take out 1 / 4 of the red ball, and then take out 7 black balls. The remaining red balls and black balls are exactly the same

Suppose: if the remaining red and black balls are both X, then the original number of red balls is (4 / 3x) and the original number of black balls is (x + 7)
The equation is as follows: (4 / 3x) + (x + 7) = 140, x = 57
The results show that the original number of red balls is (4 / 3x) = 76, and the original number of black balls is (x + 7) = 64

There are 85 red balls, green balls and yellow balls of the same size, which are arranged in the order of one red ball, three yellow balls and four green balls. The glass balls of three colors each account for the total number

The red ball is 11 out of 85, the yellow ball is 33 out of 85 and 41 out of 85

There was a box of red and yellow glass balls. Five red and seven yellow glass balls were taken out at a time. After four times, the red ones were taken out, and there were three yellow balls left. This is the case

Is this a chemistry problem or a math problem?

There is a yellow ball, a white ball and a red ball in the bag. If you touch two balls at a time, what's the possibility of touching a yellow ball or a white ball

One third

There are 1 red ball, 2 green balls and 3 yellow balls in the pocket. If you feel a ball at will, what is the possibility of touching a red ball What's the possibility of touching a white ball ．

The possibility of finding a red ball is: 1 △ 6 = 16; the possibility of finding a white ball is 0. So the answer is: 16, 0

In the bag containing 10 red balls, 8 white balls and several yellow balls, touch one ball at a time. If the possibility of touching yellow balls is 1 / 7,
In the bag with 10 red balls, 8 white balls and several yellow balls, touch one ball at a time
The possibility of the ball is 1 / 7. How many yellow balls should I put in the bag?

（10+8）÷（1-1/7）
=18÷6/7
=21
21-10-8 = 3

There are six yellow balls and several white balls in the pocket. They are all the same except for the color. If you feel one of them randomly, the possibility of touching the yellow ball is 3 / 4, then the white ball is () less than the yellow ball

6 △ 3 / 4-6 = 2 (pieces)
6-2 = 4
A: the white ball is 4 less than the yellow ball

There are several red balls, yellow balls and white balls in his pocket. Dongdong touches one ball from his pocket each time with his eyes closed. Now, how many times does he have to touch at least to make sure that he can touch two balls of the same color?

Because the three kinds of balls are several, if the balls are different each time, but when we get the fourth time, we will touch a ball with the same color as the first three balls, so we need to touch at least four times to ensure that we can touch two balls with the same color. A: he needs to touch at least four times to ensure that we can touch two balls with the same color

There are 8 white balls, 5 yellow balls and 7 red balls. In order to make at least 4 balls of the same color and at least 3 balls of another color in the bag, how many balls can be taken out of the bag at most

Take eight white balls first, and then take four red ones in one yellow 8 + 4 + 1 = 13

There are 8 white balls, 7 red balls and 5 yellow balls in the bag. In order to keep at least 4 balls of the same color and at least 3 balls of another color in the bag, how many balls can you take out from the bag at most?

According to the stem analysis, only 10 balls can be taken out, that is, the remaining 10 balls in the pocket. No matter how you allocate them, there must be at least 4 balls in one of the three colors. In this case, you can ensure that there are "at least 4 balls in the same color, and at least 3 balls in another color" in the pocket. A: you can take out 10 balls at most

There are 140 red and black balls in total. Take out 1 / 4 of the red ball, and then take out 7 black balls. The remaining red balls and black balls are exactly the same