Researchers safely captured 16 river dolphins and placed a painless tag under their flipper. These river dolphins were quickly returned to the water. Two weeks later, the researchers captured 21 dolphins and found that 3 of them had already been tagged. Estimate the number of river dolphins in the Amazon River. You have to set the problem up with a proportion and variable.

Answer this question! 30 points and brainliest! only if you know the answer.

The label on the car's antifreeze container claims to protect the car between ? 40°c and 125°c. to convert celsius temperature to fahrenheit temperature, the formula is c = 5 over 9 (f ? 32). write and solve the inequality to determine the fahrenheit temperature range at which this antifreeze protects the car. ? 40 > 5 over 9 (f ? 32) > 125; ? 40 > f > 257 ? 40 < 5 over 9 (f ? 32) < 125; ? 40 < f < 257 ? 40 < 5 over 9 (f ? 32); ? 40 < f 5 over 9 (f ? 32) < 125; f < 257

Louise measured the perimeter of her rectangular scrapbook to be 154 cm. if the scrapbook is 45 cm wide, how long is the scrapbook?