Answer:
Let x be the number of pennies, and y be the number of nickels.
1 penny = 0.01 dollar
1 nickel = 0.05 dollar.
The equations that will describe the given problem will be,
0.01 x + 0.05 y = 0.81
y = x + 9
Plugging the second equation into the first gives us,
0.01 x + 0.05(x+ 9) = 0.81
0.06 x + 0.45 = 0.81
0.06 x = 0.36
y = 15
So, Kennedy has 6 pennies, and 15 nickels.
Explanation: