Respuesta :

hafizseidu

Answer:

A

Step-by-step explanation:

we just substitute the value of "a" given in the above expression we get

21-2(3)

21-6=15

therobin

Answer:

a. 15

Explanation:

Step 1 - Input the value of 'a' in the expression.

21 - 2a

21 - 2(3)

Step 2 - Multiply two and three

21 - 2(3)

21 - 6

Step 3 - Subtract six from twenty one

21 - 6

15

Therefore, the value of the expression 21 - 2a if a = 3 is a. 15.