Spring #1 Has Spring Constant 80 N/m

Multiple Choice

Spring #1 has spring constant 80 N/m.Spring #2 has an unknown spring constant,but when connected in series with Spring #1,the connected springs have an effective force constant of 10 N/m.What is the spring constant for Spring #2?
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A) 70 N/m
B) 90 N/m
C) 9 N/m
D) 11 N/m
E) ​85 N/m