For all values of x. f(x)=2x and g(x) = x+1
a) find fg(3)
b) find gf(3)

Hmm i believe it would be c

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.