Question 999681
Same as a mixture problem.


x, how much 2cent pieces
y, how much 5cent pieces


{{{system(x=y+7,2x+5y=154)}}}
This is apparently a simple linear system application for counts of items and the cost of a combination of those items.  Note very carefully that the cost account equation is in units of CENTS, not dollars.


You can make the substitution in the system.
{{{2(y+7)+5y=154}}}
{{{2y+14+5y=154}}}
{{{7y=154-14}}}
{{{7y=140}}}
{{{highlight(y=20)}}}-------the count of the 5 cent pieces.