dime=10 cents
nickles=5 cents
835=10d+5n
divide both sides by 5
167=2d+n
total number of coins is 97
97=d+n
we have
2d+n=167
d+n=97
multiply 2nd equation by -1 and add them
2d+n=167
-d-n=97 +
1d+0n=70
d=70
sub back
d+n=97
70+n=97
minus 70 both sides
n=27
70 dimes