The given inequality is:
-40 km < -15 km
This inequality is comparing the depth of a crater in South Africa (-40 km) with the depth of a crater in Canada (-15 km).
The meaning of this inequality is that the depth of the crater in South Africa is less than the depth of the crater in Canada.
In other words, the South African crater is shallower or less deep compared to the Canadian crater.
The negative sign indicates that both craters are below the surface level, with the South African crater being deeper in the negative direction compared to the Canadian crater.