Question 1144034
 5 cent piece=  ${{{0.05 }}}
10 cents piece=  ${{{0.10}}}
 ninety nine 10 cents pieces = ${{{99*0.10}}}=${{{ 9.9}}}

let number of 5 cent pieces be {{{n}}}, and to make ${{{10}}} you need

{{{n*0.05+99*0.10=10}}}.......solve for {{{n}}}

{{{n*0.05+9.9=10}}}

{{{n*0.05=10-9.9}}}
 

{{{n*0.05=0.10}}}

{{{n=0.10/0.05}}}

{{{n=10/5}}}

{{{n=2}}}


so, you will need {{{2}}} 5 cent pieces