Question

andrea and beto are siblings. andrea is 3 years older than beto, and the sum of their ages is 31. which of the following systems of equations could be used to find andreas age, ( a ), and betos age, ( b )?
choose 1 answer:
a ( a - b = 3 )
( a + b = 31 )
b ( a + 3 = b )
( a + b = 31 )
c ( a - b = 3 )
( ab = 31 )
d ( a + 3 = b )
( ab = 31 )

Explanation:

Step1: Translate age difference to equation

Andrea is 3 years older than Beto, so $a - b = 3$.

Step2: Translate age sum to equation

The sum of their ages is 31, so $a + b = 31$.

Step3: Match to options

The system matches option A.

Answer:

A. $a - b = 3$
$a + b = 31$