In an arithmetic sequence, the 10th term $(a_{10})$ is $30$ and the common difference is $2$. What is the 1st term $(a_1)$ ?

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Using the explicit formula for arithmetic sequences:

$$a_n = a_1 + d(n-1)$$ $$a_{10} = a_1 +2(10-1)$$ $$30 = a_1 + 2(9)$$ $$a_1 = 30-18$$ $$a_1 = \boxed{12}$$