Sarah is a computer engineer and manager and works for a software company. She receives a fixed annual increase in the number of projects she handles each year. She worked on 129 projects in the fourth year of her employment and 207 projects in her tenth year

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Step-by-step explanation:

You didn't say what you'll like to calculate but let me help out.

Fourth year = 129 project.

Tenth year = 207 projects

We can form this into an arithmetic progression

Tn = a + (n-1)d

4th year = a + 3d = 129 i

10th year = a + 9d = 207 ii

Subtract equation i from equation ii

6d = 78

d = 78/6 = 13

This means that 13 new projects are added every year

For the first year, the number of projects done was:.

a + 3d = 129

a + 3(13) = 129

a + 39 = 129

a = 129 - 39 = 90

She worked on 90 projects in the first year.

c

step-by-step explanation:

it's d

step-by-step explanation: