This is another example where there is no real need in EN to use 'to know how to' — and suggesting they know how to do it 'very well' sounds rather comical — as if someone else knows how to play it badly! Once again, here, the sense is really simply 'can', though even that is unnecessary, EN can make it nice and simple.

Interesting point in the soruce text, since 'savoir très bien...' can also be some kind of a reproach — "Now don't make that excuse, you're just being lazy — you know perfectly well how to do the washing up!"

Perhaps this was not the best example the prof might have chosen.

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Note added at 3 heures (2018-03-17 20:10:50 GMT)
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Thanks to Writeaway for bringing up this usage, where 'savoir' seems, at least emiricially, to have a sense of 'pouvoir' — and which I've certainly also encountered here in France.

In particular, there is phrase that's been used for ages, when we say in the past tense: « Il a su... » which often conveys the notion of 'was able to / managed to / succeeded in...', where it's really quite difficult to see exactly how any sesne of 'knowing how to' would really fit.