PQRS is a square and points E and F are outside the square so that PQE and QRF are equilateral triangles. The size of EQF in degree, is
Please loo at the attachment to see the drawing of this problem.
With that in mind you simply add up the 90 degree angle of the square, and because both triangles are equalateral 2 x 60 degrees to get 210 degress then you take that from 360 to get the answer of 150 degrees.
Hope thats ok!