Hhh I’m very bad at math

Answer:
See below;
Step-by-step explanation:
21 . Consider an exponential function;
[tex]Exponential Function in Form - y = a * b^x, where, a - start value, b - growth factor, x - time,\\\\Now y = f ( x ), in Other Words,\\p ( t ) = 300 * ( 0.5 )^t - Given,\\\\Through Substitution - f ( x ) = p ( t ), a = 300, b = 0.5, x = t,\\\\Conclusion ; 300 - ( start value ) - Starting Amount of Milligrams of Compound,\\0.5 - Milligrams Compound Decreases by[/tex]
Solution; Provided Directly Above