Answer
The solutions are:
a) $f(3,2) = 6.$
b) $f(-1,4) -4.$
c) $f(30,5)= 150.$
d) $f(5,y) = 5y.$
e) $f(x,2)=2x.$
f) $f(5,t)=5t.$
Work Step by Step
All we need to do here is substitute the value of the first coordinate of a given point for $x$ and the value of the second coordinate of a given point for $y$ into the expression $f(x,y)=xy.$
a) $f(3,2) = 3\times 2 = 6.$
b) $f(-1,4) = -1\times4=-4.$
c) $f(30,5)=30\times 5 = 150.$
d) $f(5,y) = 5\times y = 5y.$
e) $f(x,2)=x\times2=2x.$
f) $f(5,t)=5\times t=5t.$