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. Kathy wanted to place an order to print 400 A3-size copies of her poster. How much did she need to pay?
2. Billy placed an order to print some A4-size copies of his poster. Andy 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 $249.60. How many A4-size copies of the poster did Billy print?

(a)
Amount that Kathy needed to pay
= 70 + 400 x 0.60
= $310

(b)
Total cost = $249.60

Printing cost excluding the basic printing charges
= 249.60 - 60 - 70
= $119.60

Amount of 1 A4 copy and 1 A3 copy if the cost per piece was between 1 to 49
= 0.70 + 1.10
= $1.80

Number of sets if the number of copies that each boy printed was between 1 to 49
= 119.60 ÷ 1.8
≈ 66.4 (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
= 0.45 + 0.85
= $1.30

Number of sets if the number of copies that each boy printed was between 50 to 99
= 119.60 ÷ 1.3
= 92 (✓) (Number of sets must be a whole number and is between 50 to 99.)

Number of A4-size copies of the poster that Billy printed = 92

Answer(s): (a) $310; (b) 92