Respuesta :
Use substitution method
3a+9=54
3a+9-9=54-9
3a= 45
divide by 3
3a/3= 45/3
a= 15
Answer is a= 15
Answer:
a = 15
Step-by-step explanation:
3a + b = 54
3a + 9 = 54
3a + 9 - 9 = 54 - 9
3a = 45
3a divided by 3 = 45 divided by 3
a = 15
3 x 15 + 9 = 54
45 + 9 = 54
54 = 54
