Let x = the number of dimes
Let y = the number of pennies.
There are 8 coins, therefore
x + y = 8 (1)
The coins are worth 17 cents, therefore
10x + y = 17 (2)
Subtract equation (1) from equation (2).
10x + y - (x + y) = 17 - 8
9x = 9
x = 1
From (1), obtain
y = 8 -x = 8 - 1 = 7
Answer: 1 dime, 7 pennies.