Respuesta :

Answer:

A. 2a

Step-by-step explanation:

imagine an imaginary 1 in front of the a

3a + 7 – 1a 7

subtract numbers without variables

3a + 7 – a – 7

3a-1a

subtract 1a from 3a

2a

Answer:

A. 2a

Step-by-step explanation:

3a + 7 - a + 7

= 3a - a + 7 - 7

= 2a + 0

= 2a