Who knows what the middle part is asking

Step-by-step explanation:

Estimate means put your calculator in a drawer or under a pillow. You are not going to use it.

The question means round to the nearest 10 (as it says)

One

93 rounds to 90   (93 is only 3  away from 90)

38 rounds to 40   (38 is very close to 40. You are only 2 away).

90 - 40 = 50

If you answer 55, you should get it wrong. That's not estimating.

Two

67 rounds to 70

49 rounds to 50

70 - 50 = 20        18 is just too exact.

Three

75 is very nasty. My call would be that you can call it 70 or 80. It all depends on what you have been told about 5s. On , I think you round up. So 75 become 80

27 rounds to 30

80 - 30 = 50  

The last one is all yours.