Form 1

(a) What is the percentage increase from 80 to 120?
Is it 40/80 x 100% = 50 % ?
[It's correct since the percentage change=(change/original value)*100%]

(b) What is the overall percentage change of the number?
What does this question mean?
[It means that the percentage change between the final value and the original value ]
the final value=120*(1-40%)=120(0.6)=72<80 (which means decrease overall)
the overall decreased percentage =(80-72)/80*100%=10%

50 %

10%