Mr. Li took some money to buy popular science books for the children in the welfare home. With this money, you can buy 30 copies of "exploring nature" and 100, 000 books You can buy 20 copies of "what". If you have a set of "nature exploration" and a set of "100000 whats", how many sets can you buy with your money?

Mr. Li took some money to buy popular science books for the children in the welfare home. With this money, you can buy 30 copies of "exploring nature" and 100, 000 books You can buy 20 copies of "what". If you have a set of "nature exploration" and a set of "100000 whats", how many sets can you buy with your money?

1÷(1/30+1/20)
=1÷5/60
=12 (set)

After Mr. Li transferred one girl from the math interest group to the English interest group, 17 of the remaining students were girls. If two boys were transferred instead of the girl, 15 of the remaining students were girls. Q: how many students were there in the math interest group?

After Mr. Li transferred one girl from the math interest group to the English interest group, 17 of the remaining students were girls. If two boys were transferred instead of the girl, 15 of the remaining students were girls. Q: how many students were there in the math interest group?

After Mr. Li transferred a girl from the math interest group to the English group, one seventh of the remaining students were girls
How many students are there in this math interest group?
2. There are 20 more boys in Grade 6 than 3 / 7 of the total number in Grade 6, and 3 / 4 more girls in Grade 6. How many boys and girls are there in this grade?
Two boys

1. Suppose there are x girls, and the total number of students is constant (x-1) * 7 + 1 = x * 5 + 2 x = 4, so there are 22 students. 2. Suppose there are x girls in Grade 6, the total number is equal to the number of boys and girls (3 / 7X + 20) * (1 + 3 / 4) = x = 140

Enlarge a triangle whose base length is 5cm and height is 3cm by 2:1, and the area of the figure is () square centimeter

(5×2)×(3×2)÷2
=60÷2
=30 (square centimeter)
A: the area of the figure is (30) square centimeters

If loga ^ (1 / 3) > logb ^ 1 / 3 > 0, then the relationship between a and B is
A.1

Choose D

How to solve the equation of 1.8x + 2 * 3x + 2.5 * (164-4x) = 344?

1.8X+2*3X+2.5*(164-4X)=344
1.8x+6x+460-10x=344
10x-6x+1.8x=460-344
5.8x=116
x=20

Given the circle C: (x-1) &# 178; + (Y-2) &# 178; = 2, point P (2, - 1) passes through point P to be the tangent of circle C, and the tangent points are a and B
(1) The equation of a circle passing through P, a and B
(2) The equation of line ab

1) Because PA, CA, Pb and CB, the circle passing through P, a and B is the circle with CP as the diameter. Because | CP | ^ 2 = (2-1) ^ 2 + (- 1-2) ^ 2 = 10, the square of the radius of the circle is | CP | ^ 2 / 4 = 5 / 2, and the midpoint of CP is ((1 + 2) / 2, (2-1) / 2), that is, (3 / 2,1 / 2), so the radius of the circle passing through P, a, B is (3 / 2,1 / 2)

Given the circle n (x + 2) square + y square = 8 and the parabola C Y square = 2x, the intersection of the tangent and parabola C of the circle and a B is obtained when the slope of the tangent is 1

Let the tangent of a circle be y = x + m, from which we can get: | - 2-0 + m | / √ 2 = 2 √ 2; so m = 6, or M = - 2, let a (x1, Y1), B (X2, Y2) (1) when the tangent is y = x + 6, we can get: x ^ 2 + 10x + 36 = 0, so there is no intersection between the straight line and the parabola; (2) when the tangent is y = X-2, we can get that the equation of degree x ^ 2 + 10x + 36 = 0 has no solution, so there is no intersection between the straight line and the parabola

As shown in the figure, in square ABCD, e is on CD, and AE = EC + BC, M is the key point of CD

Please fill in the picture