Arithmetic sequence

Aug 2018
73
2
Nigeria
I need a profession ready to teach and make you understand to solve this.

Mr Smith starts a job with an annual salary of \$6400 which increases by \$240 every year. After working for 8 years, Mr Smith is promoted to a new post with an annual salary of \$9500 which increases by \$360 every year.
Calculate
1. Mr Smith's salary in the fifteenth year of service
2. Mr Smith's total earnings at the end of fifteenth year of service


HELP ME OUT...I'M CONFUSED
 
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Denis

Math Team
Oct 2011
14,592
1,026
Ottawa Ontario, Canada
Mr Smith starts a job with an annual salary of \$6400 which increases by \$240 every year. After working for 8 years, Mr Smith is promoted to a new post with an annual salary of \$9500 which increases by \$360 every year.
Calculate
1. Mr Smith's salary in the fifteenth year of service
2. Mr Smith's total earnings at the end of fifteenth year of service
Do you agree that this is the 15 years flow:
Code:
         First 8 years         :           Last 7 years
   1     2            7      8        9    10           14       15
6400 6640 ... 7840 8080  9500 9860 .... 11300 11660
If so, where are you stuck?
Were you instructed to use the "sum of arithmetic series" formula?
 
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