Answer:
The area of the rectangular lawn is 100m long and 45m wide, so it has an area of 100 * 45 = <<10045=4500>>4500m².
The three circular ponds have diameters of 20m, 10m, and 5m, so their areas are 314.16, 78.54, and 19.63 square meters respectively.
The total area of the ponds is 314.16 + 78.54 + 19.63 = <<314.16+78.54+19.63=412.33>>412.33 square meters.
The total area of the lawn that needs to be covered with grass seed is 4500 - 412.33 = <<4500-412.33=4087.67>>4087.67 square meters.
Each packet of grass seed covers 50 square meters, so Mrs Jones will need 4087.67 / 50 = <<4087.67/50=81.75>>81.75 packets of grass seed.
Each packet costs £1.49, so the total cost to Mrs Jones will be 81.75 * 1.49 = £<<81.751.49=121.78>>121.78. Answer: {121.78}.
Explanation: