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.

Question

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

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

20a+5=70

Answer 1

Let's denote the age of Key as \( a \).

If Key is the youngest sibling, then the ages of the other siblings can be represented as follows:

• Oldest sibling: \( a + 8 \) (because each sibling is 2 years apart, and there are 4 older siblings)
• Second oldest: \( a + 6 \)
• Middle sibling: \( a + 4 \)
• Second youngest: \( a + 2 \)

Now, we can add the ages of all the siblings together:

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

This simplifies to:

\[ 5a + 20 \]

According to the problem, the sum of their ages is 70. Therefore, we can set up the equation:

\[ 5a + 20 = 70 \]

So, the equation that can be used to determine the age of Key is:

\[ 5a + 20 = 70 \]

Thus, the correct response is:

5a + 20 = 70