I need some help with maths questions

I need some help on these questions, please explain in the simplest way.
Expand 3(2b - 5)
Factorise 10r + 25
Solve for x: 2x = 8

Thanks.

3(2b-5)
6b-15 [Multiply everything in the brackets by 3]

10r+25
5(2r+5) [Take out 5 as a common factor]

2x=8
x=4 [Divide both sides by 2. 2x/2=x, 8/2=4]

Expand: You simply need to multiply the numbers inside the parentheses by 3.
Factorize: You need to try and find the greatest common factor between 10 and 25 and divide each number by that factor. In this case, that factor is 5.
Solve for: Divide both sides of the equation by 2 and you will have your answer.

Expand 3(2b - 5)
multiply each term within the parentheses by the coefficient:
3*2b - 3*5 = 6b-15

Factorise 10r + 25
10r = 2*5*r
25 = 5*5*r
The only factor common to both terms is 5
10r+25 = 5(2r+5)

Solve for x: 2x = 8
divide both sides by 2
2x/2 = 8/2
x = 4

Solve for x is easy. Divide both sides by 2. You get x=4. And would expand be just distributing the 3 leaving you with 6b-15? That one im not sure. And lastly the factorise i dont know how if there isnt a 10r squared. If its like what you typed i dont know. If its squared then you have to do this big thing.

Expand 3(2b - 5) = 6b -15
Factorise 10r + 25 = 5( 2r +5)
Solve for x: 2x = 8
x= 8/2 =4