Question 1071955
"20-cent coins"?


x of 10-cent coins
y of 20-cent coins

{{{system(x+y=22,0.1x+0.2y=2.9)}}}


The money equation becomes {{{x+2y=29}}}.


{{{(x+2y)-(x+y)=29-22}}}
{{{highlight(y=7)}}}
-
{{{highlight(x=15)}}}