1. 20% of a number plus 4 / 5, and the sum is 2, find the number [with equation] 2. All 50 assignments of the class have been handed in, but the teacher said that there are 2 wrong assignments. Ask for the correct rate 3. The advertisement of some instant noodles said: "the free quantity is 25%, and the price will not be increased if the quantity is increased." now the weight of a bag of instant noodles is 120 grams. Do you know how many grams it was before the free quantity?

X/5+4/5=2 X=648/50=96%X*（1+25%）=120 X=96

Three fifths of a number is 0.5 more than 40% of it
It's urgent. There must be a calculation process

3x/5-0.4x=0.5
x=2.5
This number is 2.5

Let a and C be two points on the image of inverse scale function y = K / x, a and C are symmetric about the origin and s △ ABC = 4, then the analytic expression of the inverse scale function is obtained

What's point B?
If B is perpendicular to the foot, the analytical formula of inverse proportion is y = 4 / X or y = - 4 / X

Given that point a and point B on the number axis represent two opposite numbers AB, point a is on the left side of point B, and the distance between two points AB is 4, find two numbers ab

4÷2=2
A is - 2, B is 2

What is the difference between P (XY), P (x, y) and P (x | y) in probability theory

P (XY) is calculated with the product of XY as a variable
P (x, y) is considered to satisfy the condition of two variables X, y
P (x | y) is the probability of finding x satisfying the condition if y holds

Do trigonometric functions cosh and CH have the same meaning?

Yes, the hyperbolic trigonometric function of the two different representations

1+5-9+5-8+5-6+5-6+5-7+98-5

As shown in the figure, the rectangle and parallelogram partially overlap. The area of trapezoid A is 18 square centimeters, and the area of trapezoid B is how many square centimeters

Let BD and AE intersect at m, s a = s rectangle, abfe-s triangle, ABM s b = s parallel, abdc-s triangle, ABM and rectangle have the same height as parallelogram, so the area is equal, so s a = s b = 18

If we know that the vertex of quadratic function image is on the x-axis and the image passes through points (2, - 2) and (- 1, - 8), the analytic expression is?

∵ the vertex of quadratic function image is on the X axis
Let the analytic formula be y = a (x-m) &# 178;
X = 2, y = - 2, x = - 1, y = - 8
The results show that - 2 = a (2-m) &;
-8=a(-1-m)²
The solution is m = 1, a = - 2
Or M = 5, a = - 2 / 9
The analytic formula is y = - 2 (x-1) &# 178; or y = - 2 / 9 (X-5) &# 178;

If the two non-zero roots of the square of X + MX + n = 0 are exactly m.n, find the value of M.N.. Hope we can get the solution as soon as possible

From Weida's theorem
m+n=-m
mn=n
∵m,n≠0
∴m=1
∴n=-2

Three fifths of a number is 0.5 more than 40% of it It's urgent. There must be a calculation process