a+6d=12.......(1)
a+20d=68......(2)
solve by elimination
a is gone
14d=56
d=4
a+6*4=12
a=12-24
a=-12
68 term=a+67d=?
that reminds me the equation i use to solve is
nth=a+(n-1)d
IN AN ARITHMETICS SEQUENCE THE SEVENTH TERM IS 12 AND THE 21ST TERM IS 68. CALCULATE THE 68TH TERM.
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