Factor the expression.
k^2 + 5kf - 50f^2

a. (k-10f)(k+5f)
b. (k+10f)(k-5f)
c. (k+10f)(k+5f)
d. (k-10f)(k-5f)

B. (k+10f)(k-5f) you can tell in 2 ways.  1. if the second sign is neg then the signs in the factors are going to be one neg and one positive so that knocks out C and D.  Then you look at the second term and since the 5 is positive then the 10 has to be positive so you end up with a positive 5kf.

The second way is to FOIL them out.  When you check B you get  combine your like terms and you have your original expression of 

Hope that helps

Iwould like to think so. what’s the question you need with?

It’s 24.6 after you round to the nearest tenths the answer should be 25.0