One hundred forty divided by fourteen =?

Ten, right?

So, here’s where this is coming from: I have a camera, with two lenses.
One lens (wide) goes from 14 to 42 mm, the other one (tele zoom) from 40 to 150 mm.
(I know that in the question title I speak of 140, but bare with me)
The first lens has a magnification factor of 3 (14 times 3 is 42).
The other lens has one of, roughly, 4 (40 times 4 is 160 (I know, not 150, but again, bare with me)).
So, the two lenses together go from 14 to 150 mm (roughly 10 times magnification).
Then why do I think they have only 7 times magnification (the 3x (wide), added to the 4x (tele zoom)?

Where do I go wrong?