On commencing employment a man is paid a salary of $7200 per annum and receives annual increments of $350. Determine his salary in the 9th year and calculate the total he will have in the first 12years.

Step-by-step explanation:

From the question, we can form an equation like: S = 7200 + 350X

where S is the salary and X is year.

1. His salary in the 9th year, means X=9, so we substitute 9 into the equation to find S = 7200 + 350 (9) = 10350

2. The total he will have in the first 12years, we have:

Sum of first n terms of an AP: S = (n/2) [2a + (n - 1) d] where a is the value of the 1st term, here a is 7200 and d = 350 the common difference between terms

=> S = (12/2) [2*7200 + (12 - 1) 350] = 109500