Please help :) i am very confused

For cumulative frequency you simply add the previous frequencies up to the interval you’re at.

So frequency for <58.5 is

44(0+7+37) since that’s the number of kettles that have a length less than 58.5 cm

Applying the same logic in the next 2 table places,

77 (44+33) kettles have length <63.5

While

80 (77 + 3) kettle have length
<68.5

Angle c 37° angle a 53° angle c 90°