\( 6,9,12,15, \ldots \) (a) Find the common difference. The common difference is \( d=3 \). (Type a whole number.) (b) Find the eighth term. The eighth term is \( a_{3}=\square \). (Type a whole number.)

To find the eighth term, we can use the formula for the \( n \)-th term of an arithmetic sequence, which is given by: \[ a_n = a_1 + (n-1)d \] In this case, the first term \( a_1 = 6 \) and the common difference \( d = 3 \). Plugging in the values for the eighth term \( n=8 \): \[ a_8 = 6 + (8-1) \cdot 3 = 6 + 21 = 27 \] So, the eighth term is \( a_8 = 27 \).