You essentially want the smallest integer solution to ...
60x ≥ 350
x ≥ 350/60
x ≥ 5 5/6
The smallest integer solution to this is x = 6.
The minimum number of lengths of hose needed is 6.
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Informally, you know that dividing the required total length by the length of one hose will tell you the number of required hoses. You also know the ratio 350/60 is equivalent to 35/6 and that this will be between 5 and 6. (5·6 = 30; 6·6 = 36) The next higher integer value will be 6.
