Counting in Multiple columns

Hi All,

I am a new Excel user. Can someone help me in getting solution to below
problem:

I have following data:

Grade Suject1
A 80
B 80
C 50
A 90
B 70
A 80

How can I

1. Count only Grade is "A" and score is "80"
2. Count only Grade is "A" and "B" and score is ">=70"

Thanks, Alax