The art collector has 10 painting.
He will leave 4 to his doughter.
To calculate the number of ways he coud leave those 4 paintings we use the following for combinations without repetition:

Where n is the total number of painting: n=10
r is the amount he is going to leave: r=4
Thus we get the following result for the combinations that he can make:

Answer:
In how many ways could she leave 4 of the paintings to her daughter? 210