The phrase "activities of which" is correct and usable in written English.
It can be used when referring to specific activities in a formal context, often to clarify or specify the nature of those activities.
Example: "The committee reviewed the activities of which the members had been a part during the last year."
Alternatives: "activities that" or "activities in which".
But its way of life involves these activities of which urban people disapprove.
Gross national product (GNP) expresses a nation's total economic activities, of which transportation forms a part.
The group derives two-thirds of its revenues from recruitment activities, of which approximately half is in the public sector.
The corrupt activities of which Mr. Montesinos and others are accused generated millions of dollars in secret payments.
This may not be everyone's idea of entertainment, but the pig is at the heart of the day's activities, of which a highlight is the sausage-making.
About that time she adopted the name Luisa Moreno so as to disassociate her family from her political positions and labour activities, of which they disapproved.
The company's accounts, published in June, reveal that a Head of Security was appointed "to establish and oversee the new Security Operations Centre, the activities of which have been outsourced to cyber security experts BAe systems".
The most obvious is that social networks are simply tools: when used for activities of which we approve – like riot clean-up, or the Arab spring – their power seems unambiguously positive.
At any rate, in 1955 he emerged as one of the initiators of a reformist discussion group, the Petõfi Circle, the activities of which prepared the ground for the 1956 revolution.
The organisation Demand Progress, which Swartz helped to found, had compared the activities of which he was accused to "trying to put someone in jail for allegedly checking too many books out of the library".
My daughter didn't join in the organised teen activities, of which there seemed to be plenty, so I can't vouch for them, but it's reassuring to know that teenagers can be happy just chilling out on the boat with adults.
