Solve. \[ \begin{array}{ll}x^{2}-x-10=0 \\ \text { (Simplify your answer. Type each solution only once. Use a comma to separate answers as needed.) }\end{array} \]

Solve the quadratic equations below. (a) \( x^{2}-27=0 \)

(c) \( 3 x^{2}-x=x^{2}-5 x+6 \)

(c) \( 3 x^{2}-x=x^{2}-5 x+6 \)

(c) \( 3 x^{2}-x=x^{2}-5 x+6 \)

Students stuff envelopes for extra money. Their initial cost to obtain the information for the job was \( \$ 420 \). Each envelope costs \( \$ 0.03 \) and they get paid \( \$ 0.06 \) per envelope stuffed. Let \( x \) represent the number of envelopes stuffed. (a) Express the cost \( C \) as a function of \( x \). (b) Express the revenue \( R \) as a function of \( x \). (c) Determine analytically the value of \( x \) for which revenue equals cost. (a) \( C(x)=\square \) (C in dollars) (b) \( R(x)=\square \) ( \( R \) in dollars) (c) Revenue equals cost when \( x=\square \)