The table shows the charges for printing at a printing company. The cost per piece is based on the total number of copies to be printed. 

1. Lucy wanted to place an order to print 270 A4-size copies of her poster. How much did she need to pay?
2. Bobby placed an order to print some A4-size copies of his poster. Ken placed an order to print some A3-size copies of his poster. Both of them ordered an equal number of copies of their posters. The total cost of their orders was $209.60. How many A4-size copies of the poster did Bobby print?

(a)
Amount that Lucy needed to pay
= 20 + 270 x 0.10
= $47

(b)
Total cost = $209.60

Printing cost excluding the basic printing charges
= 209.60 - 20 - 30
= $159.60

Amount of 1 A4 copy and 1 A3 copy if the cost per piece was between 1 to 49
= 0.60 + 1.00
= $1.60

Number of sets if the number of copies that each man printed was between 1 to 49
= 159.60 ÷ 1.6
≈ 99.8 (x) (Number of sets must be a whole number and is between 1 to 49.)

Amount of 1 A4 copy and 1 A3 copy if the cost per piece was between 50 to 99
= 0.35 + 0.75
= $1.10

Number of sets if the number of copies that each man printed was between 50 to 99
= 159.60 ÷ 1.1
≈ 145.1 (x) (Number of sets must be a whole number and is between 50 to 99.)

Amount of 1 A4 copy and 1 A3 copy if the cost per piece was between 100 to 499
= 0.10 + 0.50
= $0.60 

Number of sets if the number of copies that each man printed was between 100 to 499
= 159.60 ÷ 0.60
= 266 (✓) (Number of sets must be a whole number and is between 100 to 499.)

Number of A4-sized copies that Bobby printed = 266

Answer(s): (a) $47; (b) 266