1, because passing through points (9,0) and (24,20),

So: 0=K*9+B

20=K*24+B

K=4/3，B=- 12

So: Y=4/3X- 12.

2. Assuming that the linear function is Y=KX+B, then

9 = K *(4)+B

3=K*6+B

K=-3/5，B=33/5

So Y=-3/5X+33/5.