For question 11., we look at (a) the curve for #"KNO"_3# (in green) and (b) the #35# #""^"o""C"# vertical line, and see where they intersect.
They appear to intersect #~~ 54# #"g/"100"g H"_2"O"#, so the calculation of
#115# #"g KNO"_3# #- 54# #"g KNO"_3# #= 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"#
