Respuesta :

Answer:

a) 20%

b) 50%

c) -75%

Step-by-step explanation:

Mathematically, percentage change is;

(new value -old value)/old value * 100%

(i) (90-75)/75 * 100%

= 15/75 * 100% = 20%

ii) (60-40)/40 * 100%

= 20/40 * 100% = 50%

iii) (5-20)/20 * 100% = -15/20 * 100% = -75%