Question

Key is the youngest of 5 siblings. Starting with the oldest sibling, each sibling was born 2 years apart. Together, the siblings are 70 years old.

Which equation can be used to determine the age, a, of Key?

(1 point)
Responses

5a−20=70
5 A minus 20 is equal to 70

5a+70=20
5 A plus 70 is equal to 20

20a+5=70
20 A plus 5 is equal to 70

5a+20=70

Answer 1

To determine the age of Key, we can start by finding the ages of all the siblings based on the information provided.

Let:
- Key's age = a
- The ages of the siblings can be expressed in relation to Key's age. Since the siblings are 2 years apart and Key is the youngest, we can express the ages of the older siblings like this:
- Oldest sibling: a + 8 (since there are 4 siblings above Key, each 2 years older)
- Second oldest: a + 6
- Middle sibling: a + 4
- Second youngest: a + 2
- Youngest (Key): a

Now, we can formulate the equation based on their total age:
\[
(a + (a + 2) + (a + 4) + (a + 6) + (a + 8)) = 70
\]

Simplifying the left side:
\[
5a + (2 + 4 + 6 + 8) = 70
\]
\[
5a + 20 = 70
\]

Now, we can isolate 5a:
\[
5a = 70 - 20
\]
\[
5a = 50
\]

This leads us to the equation:
\[
5a + 20 = 70
\]

Thus, the equation that can be used to determine the age \( a \) of Key is:

**5a + 20 = 70**