[tex]\it a)\ \ M(-1,\ 3)\in Gf \Rightarrow f(-1)=3 \Rightarrow (m-4)\cdot(-1)+7-3m=3 \Rightarrow \\ \\ \Rightarrow -m+4+7-3m=3 \Rightarrow 11-4m=3 \Rightarrow 11-3=4m \Rightarrow 8=4m \Rightarrow m=2\\ \\ \\ b)\ m=2 \Rightarrow f(x)=-2x+1 \\ \\ A(x,\ x)\in Gf \Rightarrow f(x)=x\Rightarrow -2x+1=x \Rightarrow 1=3x \Rightarrow x=\dfrac{1}{3}\\ \\ A\d sadar,\ \ A\bigg(\dfrac{1}{3},\ \ \dfrac{1}{3}\bigg)\in Gf[/tex]
