Devin has a change jar that contain only half dollars and pennies. he has 93 coins which add up to a total of $23.96. how many of each type of coin does he have?

Let h = half dollars (50¢ or .5)
let p = pennies (1¢ or .01)
0.5h + 0.01p = 23.96
h + p = 93
multiply top equation by (-100) to make coefficients of p opposite
-50h - p = -2396
h + p = 93
combine
-49h = -2303
simplify
h = 46
find p
46 + p = 93
subtract & simplify
p = 47

Devin has 47 pennies and 46 half dollars.