Respuesta :

apologiabiology
n+d=21
5n+10d=170

so

multiply first equation by -5 and add to other one

-5n-5d=-105
5n+10d=170 +
0n+5d=65

5d=65
divide both sides by 5
d=13

sub back


n+d=21
n+13=21
minus 13 both sides
n=8




8nickles
13 dimes