Answer
The limit is
$$\lim_{(x,y)\to(a,b)}(f(x,y)-g(x,y)) = 1.$$
Work Step by Step
It is given that
$$\lim_{(x,y)\to(a,b)}f(x,y)=4,\quad \lim_{(x,y)\to(a,b)}g(x,y)=3.$$
To get the required limit we will use the rule the limit of the sum/difference of two functions is sum/difference of limits:
$$\lim_{(x,y)\to(a,b)}(f(x,y)-g(x,y)) = \lim_{(x,y)\to(a,b)}f(x,y)-\lim_{(x,y)\to(a,b)}g(x,y) \\=4-3 = 1. $$
