Answer: I think it' s A, possibly
Answer:

Step-by-step explanation:
Multiply across.

Then Simplify.

31/7 = 4 3/7.....3/7 is less then 1/2....so the closest integer is 4
Answer: C.V=C1.V1 +C2.V2
Step-by-step explanation: C=(C1V1 + C2V2)/V -> C=(20%.V+25%V)/2V-> C=22,5%