Answer:
75
Step-by-step explanation:
Since the ratio between flamingos and chachalacas is 2:1, we see that the ratio of flamingos to chachalacas to parrots to herons is 10:5:7:3. The sum of these numbers is 25, so every 'ratio number' gets 375/25 = 15 animals. So the number of chachalacas is 15 * 5 = 75.
We have the following expression

This is equivalent to

Since

we have that

Therefore, the answer is the second option from top to bottom.
Since there are no numbers, i will assume that the length of recess is 1 minute, or x. if social studies is 4 more than 2 times the length of recess, we can use the equation x*2+4 to solve the problem. the end result will be 6 minutes. Social studies is 6 minutes longer than recess
Amount left = $450 - $171 = $279
Amount left in Percentage = 279/450 x 100 = 62%
Answer: (C) 62%