How to solve (1-2 / 5) x + 8 = 80% x-4 equation （1-2/5）x+8=80%x-4 How to solve the equation

How to solve (1-2 / 5) x + 8 = 80% x-4 equation （1-2/5）x+8=80%x-4 How to solve the equation

3/5x+8=0.8x-4 0.6x+12=0.8x 12=0.2x x=60

How to solve (130-x) / (70 + x) = 1 / 4 equation?

(130-x)/(70+x)=1/4
4(130-x) =(70+x)
520-4x=70+x
520-70=5x
x= 90

A, B and C work together to make a batch of parts. A processes two fifths of the total number. A processes 125 more parts than B, and B processes one-half of a and C
How many parts are there in this batch

Hello
B accounts for 1 / 2 of the total number (1 / 2 + 1) = 1 / 3
A total of 125 (2 / 5-1 / 3) = 125 / 1 / 15 = 1875
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7x + 42 two 45 solution equation

7x=45-42
7x=3
x=3÷7
x=3/7

The weight of rice stored in warehouse A and warehouse B is 8:7. If a quarter of the rice is transported from warehouse A and 8 tons is transported into warehouse B, then a is 17 tons more than B, and the original rice in warehouse A is () t?

If a has x tons of rice, then
Rice number of B = 7 / 8x
3/4x-17=7/8x-8
X = 72 tons
Rice quantity of B = 63 tons
A warehouse original rice 72 tons

1.12x²-3y²
2.（m+n）²-4m（m+n）+4m²
3.a²+2a（b+c）+(b+c)²
The "&" above is square

12x^2-3y^2
=3(4x^2-y^2)
=3(2x+y)(2x-y)
（m+n）^2-4m（m+n）+4m^2
=(m+n-2m)^2
=(n-m)^2
a^2+2a（b+c）+(b+c)^2
=(a+b+c)^2

Given that a = 2 / 1 (half) - 2n + 1, B = 2 / 1 (half) - 2n + 3, C = 2 / 1 (half) - 2n + 2, it is the easiest way to find a 2 (square of a) + B 2 (square of B) + C 2 (square of C) - AB AC BC
a+1)(2a-3)-(a-1)(2a+3)

A ^ 2 + B ^ 2 + C ^ 2-ab-ac-bc = 1 / 2 [2A ^ 2 + 2B ^ 2 + 2C ^ 2-2ab-2ac-2bc] = 1 / 2 [(A-C) ^ 2 + (a-b) ^ 2 + (b) ^ 2 + (b) ^ 2 + (a-b) ^ 2 + (a-b) ^ 2] = 1 / 2 [2A ^ 2 + 2B ^ 2 + 2C ^ 2-2ab-2ac-2bc] = 1 / 2 [(A-C) ^ 2 + (a-b) ^ 2 + (b) ^ 2] = 1 / 2 [(A-C) ^ 2 + (a-b) ^ 2 + (a-b) ^ 2] = 1 / 2

In {an}, A3 = 7, the first three terms and S3 = 21, then q is the common ratio=______ ．

From A3 = 7, S3 = 21, we can get: a1q2 = 7a1 (1 + Q) = 14, we can get q = - 0.5 or 1, so the answer is - 0.5 or 1

How many ways to calculate 12.5 × 8.8
Don't omit

12.5*8.8=11012.5*8.8=12.5*（10-1.2）=12.5*10-12.5*1.2=125-15=11012.5*8.8=(10+2.5)*8.8=10*8.8+2.5*8.8=88+22=11012.5*8.8=(13-0.5)*8.8=13*8.8-8.8*0.8=114.4-4.4=110

In trapezoidal ABCD, ad is parallel to BC, and the median EF is 2.6cm. EF intersects AC and BD with m and N respectively, and Mn is 0.8cm

EF=1/2(AD+BC)——AD+BC=5.2CM
EM=NF=1/2BC
EM+NF=2.6+0.8=BC=3.4CM
So ad = 1.8cm BC = 3.4cm