Answer:
(a) $6000
(b) 12.5%
Step-by-step explanation:
(a): Let his old salary be X
7200 = 120% (bc it has an increase of 20%)
x = 100% (bc it was the original salary without an increase or decrease)
Cross multiply: X= 720000/120
X=6000
The answer is $6000
(b): Percentage change= {(new value-old value) / old value} * 100
His new salary is 8100, and his old salary is 7200
So: (8100/7200) / 7200 = 0.125 * 100 = 12.5
The answer is 12.5%
Hope this is right