One wreck lies at a height of -220 metres and another at a height of -85 metres. By how many metres do the two heights differ? Enter the difference in metres.

Explication

Both wrecks lie beneath sea level, so the gap between them is what remains once the smaller depth is taken from the larger one, and two hundred and twenty less eighty-five is one hundred and thirty-five. Adding the two depths would treat the wrecks as though one lay above the surface and the other below it.