Answer: The greatest number that can be safely lifted is 71 crates.
Step-by-step explanation: The crane has been described as having a breaking strain of 6400 kg (approximately). This implies that once the total capacity of crates lifted reaches the 6400 kg mark, the cable has a tendency to break. However it can lift crates which has an individual weight of 90 kg.
To find the maximum number of 90 kg crates that can be lifted at once we shall divide 6400 kg by 90 kg
Max No of crates = 6400/90
Max No of crates = 71.1111
Note however that the crates cannot be in fractions, hence the result shall be rounded to the nearest whole number.
Therefore, the greatest number of crates that can lifted without breaking the cable is 71 crates
**A quick check shows that 71 x 90 kg = 6,390 kg**
