2 times of 1.6 is 0.4 less than 25% of a number. Find this number by solving the equation. Times of browsing: 3 times reward points: 0 | there are 14 days and 23 hours to the end of the problem

2 times of 1.6 is 0.4 less than 25% of a number. Find this number by solving the equation. Times of browsing: 3 times reward points: 0 | there are 14 days and 23 hours to the end of the problem

Let this number be X
1.6×2=25%x-0.4
3.2=25%x-0.4
25%x=3.6
x=3.6÷25%
x=14.4
A: that's 14.4

2 / 7 of a number is 3 less than 2 times of 3.6. What is the number? (lie equation)

Let this number be X
3.6 times 2x of 2-7 = 3
2X of 7.2-7 = 3
2X of 7 = 4.2
X = 4.2 △ 2 / 7
x=14.7
So this number is 14.7

How to solve the system of equations composed of X + y + (y + 7) = 100 and X - [y + (y + 7)] = 2

Take y + (y + 7) as a whole for the time being
The addition of two formulas leads to 2x = 102 and the solution to x = 51
Take x into equation one
Original formula = 51 + 2Y + 7 = 100
2y=100-51-7
2y=42
y=21

It is known that if the value of Y in the system of equations 2x-y-4k = 0 14x-3y-20 = 0 is three times of X, then K=

If the value of Y in the system of equations 2x-y-4k = 0 14x-3y-20 = 0 is three times of X, then K=
Let x = m, then y = 3M
Substituting into the system of equations
2m-3m-4k=0.(1)
14m-9m-20=0.(2)
From (1), M = - 4K
Substituting the solution in (2), we get - 20k-20 = 0
That is k = - 1

Solve the equations (X-2) △ 4 - (y + 1) △ 5 = 1 ①(x-2)÷4+(y+1)÷5=3…… ②

①+②
(2x-4)÷4=4
2x-4=16
2x=20
x=10
Substituting x = 10 into (1) formula y = 4
∴x=10
y=4

Solve the equations {3 (x + y) - 4 (X-Y) = 11 {2 (X-Y) + 5 (x + y) = 27

It is reduced to: - x + 7Y = 11 ① 7x + 3Y = 27 ②
① Equation × 7 is: - 7x + 49y = 77 ③
② + 3: 52y = 104
∴y=2
Substituting into (1) we get: x = 3
∴x=3,y=2

To solve the equations: X / 30 + Y / 20 + (75-x-y) / 40 = 2.5 x / 30 + (75-x-y) / 20 + Y / 40 = 2.8

X/30+Y/20+(75-X-Y)/40=2.5 4X+6Y-3X-3Y =X+3Y=2.5*120-75*3
X/30+(75-X-Y)/20+Y/40=2.8 4X+3Y-6X-6Y =-2X-3Y=2.8*120-75*6
-X=5.3*120-75*9 X=75*9-5.3*120=3(3*75-53*4)=3*13=39
3Y=2.5*120-75*3 Y=2.5*40-75=25

Solve the equations 2x + y = 40, x + 1 / 2Y = 20

If your second equation is x + y * 1 / 2 = 20, it is an equation with two unknowns, XY matching countless solutions
If the second equation is x + 1 / (2 * y) = 20, the process is 2 * (x + 1 / (2 * y)) = 2 * 20) to get 2x + 1 / y = 40, then subtract the first equation to get: 1 / Y-Y = 0, to get y = 1, x = 19.5

Solve the equations 1 / (X-Y) - 1 / (x + y) = 3 / 20,2 / (x + y) + 3 / (X-Y) = 19 / 20
Let me give you a hint:
1/（x-y）-1/（x+y）=3/20 ①
2/（x+y）+3/（x-y）=19/20 ②
......
╮ (╯╭)! It seems we have to ask someone else

1/（x-y）-1/（x+y）=3/20,
2/（x+y）+3/（x-y）=19/20
Let: 1 / (X-Y) = a, 1 / (x + y) = B
a-b=3/20.1
2b+3a=19/20.2
Formula 1 * 2 + 2:
5a=6/20+19/20=25/20
a=5/20=1/4
b=a-3/20=5/20-3/20=2/20=1/10
1/(x-y)=1/4 x-y=4
1/(x+y)=1/10 x+y=10
Add: 2x = 14 x = 7 subtract: 2Y = 6 y = 3

Solving equations x + y = 500 [(1 + 50%) x + (1 + 40%) y] × 90% = 500 + 157

x+y=500
So y = 500-x
Substituting [(1 + 50%) x + (1 + 40%) y] × 90% = 500 + 157
1.35x+1.26y=657
So 1.35x + 630-1.26x = 657
0.09x=27
therefore
x=300
y=500-x=200