Respuesta :

Answer:

Lowest: 78

Highest: 99

Step-by-step explanation:

Quiz 1 =A

Quiz 2 = B

B = 21 + A

2A = 57 + B

2A = 57 + (21 + A)

2A = 78 + A

A = 78

B = 21 + A

B = 21 + 78

B = 99