There are 20 boys and 5 / 9 girls in a class. How many students are there in the class A few more Pile a coal is 4 / 5 of pile B coal. If 8 tons are transported from pile B to pile a, pile B is 40 tons more than pile A. how many tons are there in pile a and pile B? How many cuboids do you need to build a cube with a cuboid 12 cm long, 8 cm wide and 10 cm high? Xiao Ming planted a tree every 6 meters along the same road, with a total of 31 lessons. Now Xiao Ming wants to plant a tree every 8 meters without his brother. How many trees should there be without moving? 1 extra point for answering within 1 hour!

The number of female students = 20 + 5 = 25, the total number of students in the class = 25 + 20 = 45, the proportion of female students = 25 / 45 = 5 / 9, the proportion of male students = 20 / 45 = 4 / 9
Can it solve your problem?

Class 6 (1) has 20 boys and 4 / 9 girls. How many girls are there?

There are x girls
20+x=9x/4
80+4x=9x
-5x=-80
x=16

As shown in the figure, in the rectangle ABCD, ab = 10, BC = 12, point P is the midpoint of the edge of CD. Fold the rectangle ABCD so that point a coincides with point P, and point B falls at point G, then the length of crease EF is______ ．

Through point E, make em ⊥ BC at point m, ∵ fold rectangle ABCD so that point a coincides with point P, point B falls at point G, ∵ 1 = ≁ 4, ∵ 1 + ≁ 2 = 90 °, ∵ 2 + ≁ 3 = 90 °, ∵ 1 = ≁ 3, ∵ EMF = 90 °, d = 90 °, ∽ ADP ∽ EMF, ∵ DPFM = ADEM, ∵ in rectangle ABCD, ab = 10, BC = 1

Simple algorithm of 6.3 + 8.7 + 8.7 * 3.7

It's 6.3 * 8.7 + 8.7 * 3
6.3*8.7+8.7*3.7
=(6.3+3.7)*8.7
=10*8.7
=87

A question about reaction rate in chemistry of grade one of senior high school
The reversible reaction 3Fe (s) + 4H2O (g) = Fe3O4 (s) + 4h2 (g) was carried out in a closed vessel with variable volume,
With the increase of Fe content, the change of positive reaction rate is obvious
Why is it constant?
In chemistry, which conditions are related to the reaction rate and which are not?
The second question: keep the volume unchanged, rush into N2 to make the volume pressure increase, the positive reaction rate will increase Reverse reaction rate .
Why unchanged?

The factors affecting the reaction rate are: concentration, temperature, pressure, catalyst, surface area, light, sound wave, etc
The original intention of this problem is to increase the concentration of Fe, but Fe is a pure solid. Increasing the amount of Fe has no effect on the concentration, so the rate does not change
2. The effect of pressure on the rate is finally reflected by the change of concentration. If the change of pressure does not lead to the change of reactant concentration, it has no effect on the rate
In the second question, the total pressure of the system increases with the addition of N2, but the concentration of H2O does not change, so the forward and reverse rates do not change
Chemistry teacher. Leave a footprint

The area of a triangle is a few percent of the area of a parallelogram with the same base and height

1/2=50/100=50%

-3 5 - 13 7 count 24

The calculation is as follows: [7 - (- 13) × 5] △ 3 = 24

Fifth grade volume I off form calculation
Fifth grade volume I with decimal off formula calculation questions (excluding fractions) 50
Example: (52.3 + 96.5) * 61 / 3.5=
Don't copy other people's questions

(2296+7344÷36)×2.4 1÷0.45÷0.90.36×[(2＋3.8)÷0.04] (8－1.24)÷3 45×9.9 4.82×88+48.2×1.2 4.2×102－8.4 7.86－(5.63－0.86)－1.3733.02－（148.4－90.85）÷2.5（1÷＋÷1）÷5.1

As shown in the figure, in ladder ABCD, the bisector of ∠ ABC and ∠ DCB intersects at a point P on ladder median line EF. If EF = 3, the circumference of ladder ABCD is ()
A. 9B. 10.5C. 12D. 15

The median line of ∵ EF trapezoid is ∵ EF ∥ BC, AD + BC = 2ef = 6. ∵ EPB = ∵ PBC. Because BP bisects ∵ EBC, ∵ EPB = ∵ EBP, ∵ be = EP, ∵ AB = 2ep. Similarly, CD = 2pF, so AB + CD = 2ef = 6. Then the circumference of trapezoid ABCD is 6 + 6 = 12

The square + (2m + 1) x + M = 0 of the equation MX of X has two real roots, then the value range of the real number m is?

Δ > 0 and m ≠ 0.4m & # 178; + 4m + 1-4m & # 178; > 0
m> - 1 / 4 and m ≠ 0