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

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

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

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

5a−20=70

Answer 1

To determine the age of Key, we start by understanding the problem.

Let Key's age be \( a \). Since Key is the youngest of 5 siblings, the ages of the other four siblings can be expressed in relation to Key's age:

- The next sibling (second youngest) is \( a + 2 \)
- The next sibling is \( a + 4 \)
- The next sibling is \( a + 6 \)
- The oldest sibling is \( a + 8 \)

Now, the sum of the ages of all five siblings can be written as:

\[
a + (a + 2) + (a + 4) + (a + 6) + (a + 8)
\]

Combining all the terms, this simplifies to:

\[
5a + (2 + 4 + 6 + 8) = 5a + 20
\]

We know that the total age of all the siblings is 70 years, so we set up the equation:

\[
5a + 20 = 70
\]

Thus, the equation we can use to determine Key's age \( a \) is:

\[
5a + 20 = 70
\]

So the correct response is:

**5a + 20 = 70**