How many different ways when we take 7 numbers from 49 lottery numbers, and from 7 of these numbers there are 3 correct numbers? (kombination)

⁴⁹C₇ = 85,900,584 this is the total ways if we select 7 numbers out of 49.

among that number only 3 are correct, so ⁷C₃ = 35 are correct

If ⁷C₃ are correct, means the remaining incorrect are ⁽⁴⁹⁻⁷⁾C₄ =⁴²C₄
And the total ways of getting 3 correct numbers is :

⁷C₃ x ⁴²C₄ = 3,917,550

1.17+3.99a. you combine the terms with a to create 3.99 and the 1.17 stays because it has no like terms or a variable