A concert promoter needs to make $42,000 from the sale of 1800 tickets. The promoter charges $20 for some tickets and $30 for the others. Let x represent the number of $20 tickets and y represent the number of $30 tickets.

(a) Write an equation that states that the sum of the tickets sold is 1800.

(b) How much money is received from the sale of $20 tickets?

(c) How much money is received from the sale of $30 tickets?

(d) Write an equation that states that the total amount received from the sale is $42,000.

(e) Solve the equations simultaneously to find how many tickets of each type must be sold to yield the $42,000?