What does economy mean plz tell me

Pelle's sister is three years older than pelle the father is 5 times as old as pelle the mother was 28 when the sister was born altogether they are 98 years old how old is pelle?

Bruce is getting materials for a chemistry experiment his teacher gives him a container that has 0.25 liter of liquid in it. bruce need to use 0.4 of this liquid for the experiment. how much liquid will bruce use?

20 solve 2(4 x + 3) < 5 x + 21. a) { x | x < 9} b) { x | x > -5} c) { x | x > -9} d) { x | x < 5}