How much sugar will dissolve in 1000 g of water at 80°c?

If we look at the sugar-water phase diagram;
at 80° C : 26% of water will dissolve 74% of sugar
C =  m / ( m + 1000 g ) · 100
74 = m / ( m + 1000 g ) · 100
0.74 = m / ( m + 1000 g )
m = 0.74 · ( m + 1000 g )
m = 0.74 m + 740 g
m - 0.74 m = 740 g
0.26 m = 740 g
m = 740 g : 0.26
m = 2,846.15 g ≈ 2,846 g

m ( sugar ) = 2,846 g.