Factor the expression.

20k + 50

To factor this expression the first thing you would need to do is to take the two terms from the expression and break the terms down into prime numbers and single variables. This would look like this:
20k: 2*2*5*k
50:2*5*5

When you look at the terms that are factored, notice that each term have in common 2*5 or the factor 10, which happens to be their greatest common factor which is just what you need in order to factor this expression. When you factor 10 from the expression, you get your answer as 10(2k+5).

TO FACTOR ANY EXPRESSION, you would need to find the common factor between the numbers in the expression that are to be factored. In this case, you're factoring 20 and 50.

All you have to do is find a common factor between them, any common factor. It can be 5, it can be 2, it can be 10,  it can be whatever goes into both numbers once multiplied.

If you were to use 2 to factor it, it would be : 2( 10k + 25)
If you were to use 5 to factor it, it would be : 5( 4k + 10)
And the greatest factor is 10, and it would be : 10( 2k + 5)