Answer:
(1) difference between correct and incorrect marks= 85-65
=20
percentage of error = difference between correct and incorrect marks/ correct marks ×100
= 20/85×100
= 23.53% ans.
(2) original salary= 16100×100/115
= 14000
or
original salary= 100%
new salary = 115% = 16100
1% = 16100/115
100% = 16100 ×100/115
= 14000