For question 11., we look at (a) the curve for "KNO"_3KNO3 (in green) and (b) the 3535 ""^"o""C"oC vertical line, and see where they intersect.
They appear to intersect ~~ 54≈54 "g/"100"g H"_2"O"g/100g H2O, so the calculation of
115115 "g KNO"_3g KNO3 - 54−54 "g KNO"_3g KNO3 = ul(61color(white)(l)"g KNO"_3
is correct.
For question 12., we look at (a) the curve for "KCl" (the diagonal dark blue line) and (b) the 80 ""^"o""C" vertical line, and see where they intersect,
The point of intersection is ~~ 52 "g/"100"g H"_2"O". Therefore, if two hundred grams of water are used, the result is double this value:
52 "g KCl" xx 2 = ul(104color(white)(l)"g KCl"
