Sudha spends 80% of her income. Whenher income is increased by 30%, she increases her expenditure by 25%. Her savings are:

let sudha's income be 100 units therefore amount she expends is 80% of income i.e 80units 

after increment of 30% that is 30% of 100 units is 30 making her income to be 130 units 

expenditure before is 80 units so 25% of 80 units is 20 making her total expenditure to be 100 units 

hence, her saving now is 130-100= 30,

her saving earlier was 100-80=20 

therefore difference in saving is 30-20=10 units

so percentage increase in saving = 10$$\div{20}$$ $$\times{100}$$

                                                      =50%