Create a model to help you solve this. Field Engineers are putting down the turf for 8 days.
Day 1: 30
1 of the whole field is put down
Day 2: 30
2 of the whole field is put down
Day 3: 5
1 of the whole field is put down
Day 4: 10
3 of the whole field is put down
Have the Engineers covered ½ of the field yet? How do you know?