Factor to this equation out, the easiest way is to solve for the two x values that add up to -1 but when multiplied is equal to -6. It should look like this: (x +- ?)(x +- ?).
The factored out form is then (x - 3)(x +2), because -3 + 2 = -1 and when multiplied together gives -6.
x - 3 = 0
x = 3
x + 2 = 0
x = -2
The two solutions are therefore, x = 3 and x = -2.
Hope it helps
2/5 , i dont have an explanation but maybe try that! I just did the math on paper
To find the answer, use 
, and then use the equation 
To find it's half life.
8/11 of what = 16
8/11x = 16
x = 16 * 11/8
x = 176/8
x = 22......so there are a total of 22 fish in the tank
