To compare, either take average month or Full year:
Consider 1 average month:
1st Scheme = (100+12)/100 * 2400
= 1.12 * 2400
= $2688

2nd scheme = (100+8)/100 * 2400 + 1000/12
= 1.08 * 2400 + 83.33
= $2675.33 (2 decimal Place)

Hence first scheme is better.

B) let new salary be S
equate both sides:
1.12 * S = 1.08 * S + 83.33
0.04S = 83.33
S = $2083.25

If new salary is $2083.25, both schemes will give same amount,
To make 2nd scheme more worthy,
Lowering the salary will make the annual bonus more worthy,
Hence the new salary: $2083 or below will make 2nd scheme better //