The answer is D, the yellow
Answer:
c + d = 400
0.2c + 0.5d = 156
Step-by-step explanation:
Let
c = number of liters of 20% acid solution
d = number of liters of 50% acid solution.
c + d = 400 (1)
0.2c + 0.5d = 400(0.39)
0.2c + 0.5d = 156 (2)
From (1)
c = 400 - d
Substitute c = 400 - d into (2)
0.2c + 0.5d = 156 (2)
0.2(400 - d) + 0.5d = 156
80 - 0.2d + 0.5d = 156
- 0.2d + 0.5d = 156 - 80
0.3d = 76
d = 76/0.3
d = 253.33 liters
Substitute d = 253.33 into (1)
c + d = 400
c + 253.33 = 400
c = 400 - 253.33
c = 146.67 liters
Answer:
It will treasure 6 years to get to 4,700 students
