Growth
y=0.1(1.25)t
y=426(0.98)t
y=2050(1/2)t
Decay
100(1-1/2)t
y=((1-0.03)1/2)2t
With growth and decay you can mostly tell which is which because if it has subtraction sign its decay and if it has addition sign or nothing that indicates subtraction then its growth.
Hope it helps!