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

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

5a−20=70
5 A minus 20 is equal to 70

5a+20=70

Answer 1

To find the correct equation that can be used to determine the age, \( a \), of Key, let's analyze the problem step by step.

1. There are 5 siblings, with ages that are 2 years apart.

2. Let’s denote their ages as follows:

   • Oldest sibling = \( a + 8 \) (where \( a \) is Key's age)
   • Second oldest sibling = \( a + 6 \)
   • Middle sibling = \( a + 4 \)
   • Second youngest sibling = \( a + 2 \)
   • Youngest sibling, Key = \( a \)

3. The total age of all siblings is given as 70 years:

\[ (a + 8) + (a + 6) + (a + 4) + (a + 2) + a = 70 \]

4. Combining like terms, we get:

\[ 5a + 20 = 70 \]

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

\[ 5a + 20 = 70 \]

Thus, the correct response is:

5a + 20 = 70