Excel: column formula with conditions

I want to find the slope and intercept of a column of data, but I want to include an IF function that looks at another column and only counts the data if the condition is met.

Example:

1   54  23
2   34  52
2   25  93
2   13  53
1   88  54

I want to find the SLOPE and INTERCEPT of these variables ONLY WHEN the type is 2.

I know the syntax would be =SLOPE(B:B) but how do I add conditionals?