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

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18

christopher is 272,195 year old

step-by-step explanation: