To determine the tip amount for Delilah and her group of friends, let's break down the process step-by-step:
1. Identify the total bill amount: We begin with a total bill of $140.
2. Understand the percentage to be tipped: The group decided to give a 25% tip.
3. Convert the percentage to a decimal form: To make calculations easier, percentages should be converted to a decimal. This can be done by dividing the percentage by 100. In this case, 25% becomes \( \frac{25}{100} = 0.25 \).
4. Calculate the tip amount: Multiply the total bill by the decimal form of the percentage. This gives us:
[tex]\[
140 \times 0.25 = 35.0
\][/tex]
5. Result: The amount of the tip Delilah and her friends should leave is \( \$35.0 \).
So, using the diagram and this explanation, we identify the amount of the tip as:
[tex]\[
\$ \boxed{35.0}
\][/tex]