Verified answer

In an ideal transformer the volts per turn are the same for all coils in the transformer.  if 18 turns gives 69 v then you have 69/18 volts for every turn anywhere in the transformer.  Hence in the primary you have 11 * 69/18 ~= 42 V peak

@billrussell42 its cop pasted from a homework assignment

idk the answer because I havent taken physics sorry

as shown in the drawing ??