Answer:
k = 10.5
Step-by-step explanation:
8/7 = 12/k
Using cross products
8k = 7*12
8k = 84
Divide each side by 8
8k/8 = 84/8
k = 10.5
Answer
Let t be number of minutes since tap is opened
water is increased by 20 gallons of water per minute.
sugar increase rate of 3 pounds per minute
water :- W(t) = 350 + 10 t
sugar :- S(t) = 10 + 3 t
concentration
C(t) = 
at t = 15 minutes
C(15) = 
C(15) = 
C(15) = 0.11
at beginning t = 0 minutes
C(0) = 
C(0) = 
C(0) = 0.0286
C(15) > C(0)
hence, concentration is increasing as time is passing.
Answer is A
7 + 2X = 2(X-1) + 4
7 + 2X = 2X-2+4
7 + 2X = 2X + 2 whether 2X = 2X-5 or 5 + 2X = 2X still 0 = 5 Or 0= -5 which is not possible