PLZ HELP ME ANSWER THIS QUESTION QUICK!
At the Melbourne Aquarium, six of the sea creatures are not Turtles, but the rest are. There is the same number of Fish as Turtles, but only half as many Sharks and Dolphins. The number of Squids are equivalent to the Sharks and Dolphins combined. How many Turtles are there at the Aquarium?

A: 1

B:2

C:4

D:6

E:7

The answer is D:6 but can someone explain to me why and how?

Which of these numbers of simulations of an event would be most likely to produce results that are closest to those predicted by probability theory? 15, 20, 5, 10

Write 5(6x+4)-2(5x-2) in the form a(bx+c) where a,b and c integers and a> 1

Anew test for ra is being developed. the test is administered to 750 patients with ra and 750 without ra. for the sake of the question, assume the prevalence of ra in this population is 50%. of the 750 patients with ra, 575 have a positive result. of the 750 patients without ra, 150 have a positive result. what is the positive predictive value of the new test? a575/(575+150) b. 600/(600+ 150) c. 575/(575+125) d. 600/(600+ 125)