Answer:
20/3
7x - 8 = 4(x+ 3)
Step-by-step explanation:
Let the unknown number be x.
Now, the difference between 7 times a number and 8 is equal to four times the sum of the number and 3.
Writing this mathematically:
7x -8 = 4(x + 3)
To solve completely, we open the bracket:
7x - 8 = 4x + 12
7x - 4x = 12 + 8
3x = 20
x = 20/3
The correct equation to solving the problem is 7x - 8 = 4(x + 3)
Answer:

Step-by-step explanation:
The formula of a volume of a cube:

a - length of the edge
We have a = 8cm. Substitute:

The volume of second cube:

The length of the edge of the second cube (b):
![b^3=1024\to b=\sqrt[3]{1024}\ cm^3](https://tex.z-dn.net/?f=b%5E3%3D1024%5Cto%20b%3D%5Csqrt%5B3%5D%7B1024%7D%5C%20cm%5E3)

Used 
![b=\sqrt[3]{1024}=\sqrt[3]{2^{10}}=\sqrt[3]{2^9\cdot2}=\sqrt[3]{2^9}\cdot\sqrt[3]{2}](https://tex.z-dn.net/?f=b%3D%5Csqrt%5B3%5D%7B1024%7D%3D%5Csqrt%5B3%5D%7B2%5E%7B10%7D%7D%3D%5Csqrt%5B3%5D%7B2%5E9%5Ccdot2%7D%3D%5Csqrt%5B3%5D%7B2%5E9%7D%5Ccdot%5Csqrt%5B3%5D%7B2%7D)
Use 
![=\sqrt[3]{2^{3\cdot3}}\cdot\sqrt[3]{2}=\sqrt[3]{(2^3)^3}\cdot\sqrt[3]{2}](https://tex.z-dn.net/?f=%3D%5Csqrt%5B3%5D%7B2%5E%7B3%5Ccdot3%7D%7D%5Ccdot%5Csqrt%5B3%5D%7B2%7D%3D%5Csqrt%5B3%5D%7B%282%5E3%29%5E3%7D%5Ccdot%5Csqrt%5B3%5D%7B2%7D)
Use ![\sqrt[3]{a^3}=a](https://tex.z-dn.net/?f=%5Csqrt%5B3%5D%7Ba%5E3%7D%3Da)
![=2^3\sqrt[3]{2}=8\sqrt[3]{2}\ cm](https://tex.z-dn.net/?f=%3D2%5E3%5Csqrt%5B3%5D%7B2%7D%3D8%5Csqrt%5B3%5D%7B2%7D%5C%20cm)
![\sqrt[3]{2}\approx1.26\to b\approx8(1.26)\approx10.1\ cm](https://tex.z-dn.net/?f=%5Csqrt%5B3%5D%7B2%7D%5Capprox1.26%5Cto%20b%5Capprox8%281.26%29%5Capprox10.1%5C%20cm)
Other method:
![V'=2V\\\\V=a^3,\ V'=b^3\to b^3=2a^3\to b=\sqrt[3]{2a^3}\\\\b=a\sqrt[3]2](https://tex.z-dn.net/?f=V%27%3D2V%5C%5C%5C%5CV%3Da%5E3%2C%5C%20V%27%3Db%5E3%5Cto%20b%5E3%3D2a%5E3%5Cto%20b%3D%5Csqrt%5B3%5D%7B2a%5E3%7D%5C%5C%5C%5Cb%3Da%5Csqrt%5B3%5D2)
![a=8\ cm\to b=8\sqrt[3]2\ cm\approx10.1\ cm](https://tex.z-dn.net/?f=a%3D8%5C%20cm%5Cto%20b%3D8%5Csqrt%5B3%5D2%5C%20cm%5Capprox10.1%5C%20cm)
C three times a number less seven is greater than or equal to twenty.solve for x
Answer: 9 Presents
Explanation: 15/3 = 45/x.
Cross Multiply: 15x= (45)(3)
Simplify: x= 9