Answer:
-3 and -7/3
Step-by-step explanation:
You could solve by factoring.
To do that, you find 2 numbers that multiply to 21, but add up to 16 when you multiply one of them by 3.
In this case, 3 and 7 would work, because 3*3 + 7 = 16, and 3 * 7 = 21.
Therefore, we can factor the equation to (3x+7)(x+3).
The solutions of the equations are -3 and -7/3.