i dont know if you want me to answer them or not, but you have to COMBINE LIKE TERMS if you dont then your problems would be messed up example if you have a+a it would be 2a make sense? so you want everything combined then you have to solve. theres no possible way of solving these without numbers number would have to be added although youll probably end up getting rid of the numbers in the end. after you combine like terms do the rest of solving
hope that helps if you need more help pm me, :)
2.50 (5) = 12.5
she owes 12 dollars and 50 cents
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
Remember you can do anything to an equaiton as long as you do it to both sides
-x=4-3x
add 3x both sides
3x-x=4+3x-3x
2x=4+0
2x=4
divide 2
2x/2=4/2
2/2x=2
1x=2
x=2
Answer:
Yes, 2 is a rational number.