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

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