Well, darling, the least number that rounds to 80 when rounded to the nearest 10 is 75. You see, when you round 75 to the nearest 10, it becomes 80. So, there you have it, simple math for a simple question.
It is: 10
75 rounded to the nearest ten is 80
75
80
100
100
33.3*75 = 2497.5 Rounded to the nearest whole, it's 2498.
75.0
8 is already rounded to the nearest 10th. Rounded to the nearest 10 is 10.
It is 75
75.0