The sum of 2 numbers which are in a ratio 2:5 is 21 what are the numbers

The number of fish in a lake can be modeled by the exponential regression equation y=14.08 x 2.08^x where x represents the year

Two cars which are 40 miles apart start moving simultaneously in the same direction with constant speeds. if the speed of the car which is behind is 56 mph and the speed of the other car is 48 mph, how many hours will it take for the car which is behind to catch up the car ahead of it?

In the equation sqrt(n+5)-sqrt(11-10)=1. what is the value of n