\begin{aligned} &\text { 1. }\\ &f(x, y)=\frac{x+y}{30}, \quad \text { for } x=0,1,2,3 ; y=0,1,2 \end{aligned} ^^20(a)^^20P(X\leq2,Y=1); ^^20(b)^^20P(X>2,Y\leq1); ^^20(c)^^20P(X>Y); ^^20(d)^^20P(X+Y=4);