Question 890324
The formula should really be {{{y=100(10)^(-0.4x)}}}


Just substitute the given values of x to answer (a), (b), and (c).
Table of common logarithms or scientific calculator are the tools to use


Using (b) as example, {{{y=100*10^(-0.4*3)}}}
{{{y=100*10^(-1.2)}}}
{{{y=100*6.303*(10^(-2))}}}
{{{y=6.3}}}