Shawntee has 21 coins all of them nickel and dimes that are worth $1.70. Write a system of equations and splve

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