Algebra：練習問題

Solve the following equation:
\(k + 18 = 42\)

Solve the following equation for \(y\):
\(\frac{y}{6} - 3 = 2\)

The diagram shows a sequence of figures made of circles. If the number of circles continues to grow in the same pattern, how many circles will there be in the \(10\)-th figure?

Simplify the following algebraic expression:
\(9x - 5x + 2x\)

If \(\frac{2x - 5}{3} = 7\), what is the value of \(x\)?

A book costs \(x\) dollars. A pen costs \(5\) dollars less than the book. What is the total cost, in dollars, of one book and one pen in terms of \(x\)?

A baker uses \(k\) kilograms of flour to make a batch of \(12\) identical cakes.
(a) Write an algebraic expression for the amount of flour used for each cake in terms of \(k\).
(b) If the baker needs to make \(30\) such cakes, write an algebraic expression for the total amount of flour required.
(c) If \(k = 2.4\), calculate the total amount of flour needed for the \(30\) cakes.