Question 129532
Let {{{d}}} = number of dimes
Let {{{n}}} = number of nickels
{{{n = 2d}}}
{{{5n + 10d = 420}}}
{{{5*(2d) + 10d = 420}}}
{{{20d = 420}}}
{{{d = 21}}}
{{{n = 2d}}}
{{{n = 42}}}
Joe has 42 nickels and 21 dimes
check answer:
{{{5n + 10d = 420}}}
{{{5*42 + 10*21 = 420}}}
{{{210 + 210 = 420}}}
{{{420 = 420}}}
OK