Let f(x)= 4*+1 & g(x)=3x+k if (gof) (x)=(fog)(x),then find k

Which statements are true? see picture

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Hassan bought a package of tofu. the temperature of the tofu was 14° celsius when hassan put the package into the freezer. he left the tofu in the freezer until it reached –19° celsius. which expressions explain how to find the change in temperature, in degrees celsius, of the package of tofu? select three that apply.