Calculate the Deficit: $10 Budget vs $20 Purchase Problem

To solve this problem, let's work through it step-by-step:

• Step 1: Identify what Daniel has and what he wants to do.
• Step 2: Use the subtraction operation to calculate the money left after the purchase.

Step 1: Daniel starts with \10 \).
Step 2: He wants to buy cookies costing \20 \).

Using the subtraction formula to find the remaining money:

\text{Remaining Money} = \10 - \$20$

This calculation yields:

\10 - \20 = -\10\)

This result means Daniel will have -\10\) left, indicating he lacks 10 to make this purchase.

The correct solution to the problem is \(\boxed{-10}.