A quantity starts with a size of 250\displaystyle {250} and shrinks by 60%\displaystyle {60}\% per year.

Construct a function A(t)\displaystyle {A}{\left({t}\right)} that models the growth of the quantity:
A(t)=\displaystyle {A}{\left({t}\right)}=  

Write an expression for the size of the quantity after 50\displaystyle {50} years. Leave your answer in exponential form; do not give a decimal approximation.
The size will be   .