Place Value Problem: Finding Numbers with Hundreds Digit 5 and Units Digit 7

To solve this problem, we'll follow these steps:

• Step 1: Analyze each number into its hundreds, tens, and units digits.
• Step 2: Check for a hundreds digit of 5 and a units digit of 7.

Here are the given numbers:

• $587$: Hundreds $= 5$, Units $= 7$.
• $517$: Hundreds $= 5$, Units $= 7$.
• $570$: Hundreds $= 5$, Units $= 0$.

Now, let's identify which numbers meet the criteria:
- $587$ has a hundreds digit of 5 and a units digit of 7, so it meets the criteria.
- $517$ also has a hundreds digit of 5 and a units digit of 7, meeting the criteria.
- $570$ does not meet the criteria because its units digit is 0.

Therefore, both numbers $587$ and $517$ meet the condition. According to the choices given:

The correct answer is: Equations (a) and (b) are correct.