Initially, the jar has $28, which is equivalent to 28 * 4 = 112 quarters (because each dollar is made up of 4 quarters).
Let \( C \) be the number of quarters Christine added, and \( T \) be the number of quarters Ty added.
The new amount of quarters in the jar after both contributions would be:
\[ 112 + C + T \]
To convert this back into dollars, we divide by 4 (since there are 4 quarters in a dollar):
\[ \frac{112 + C + T}{4} \]
Now, adding this to the initial $28, the total amount of money in the jar now, \( M \), can be represented as:
\[ M = 28 + \frac{C + T}{4} \]
Thus, the expression that represents the amount of money in the jar now is:
\[ 28 + \frac{C + T}{4} \]