Penny = 0.01
Nickel = 0.05
He saved up a total of 474 coins
x + y = 474
Where:
x = number of pennies
y= number of nickels
There is a total of 11.22 in his bank:
0.01x + 0.05y = 11.22
We have the system of equations:
x + y = 474 (a)
0.01x + 0.05y = 11.22 (b)
Solve (a) for x :
x = 474-y
Replace x on (b) and solve for y:
0.01 (474-y) + 0.05y = 11.22
4.74 -0.01y +0.05y = 11.22
-0.01y+0.05y = 11.22-4.74
0.04y = 6.48
y= 6.48/0.04
y= 162
Replace y on (a) ans solve for x
x+y= 474
x + 162 = 474
x = 474 -162
x = 312
312 pennies
162 nickels