This involves a bit of logic in thinking about what LCM actually means.
LCM is the least common multiple. A
common multiple is a multiple shared by two or more numbers. And by
multiple, we mean some number multiplied by successive integers; this set contains multiples of 5 {5, 10, 15, 20, 25...}. You can see that the least (or lowest) common multiple is the lowest multiple shared by two numbers. Like for 6 and 9, you have {6, 12,
18, 24...} and {9,
18...}, so LCM(6,9) = 18.
Now, if an LCM must be shared by both numbers, and to get a multiple of the largest number, you have to multiply by an integer greater than or equal to 1, then the LCM of two numbers can never be less than the larger of the twi numbers. Generally, if x and y are positive real numbers, and x is greater than y,

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Answer: Mark up percent = 20%
Step-by-step explanation:
Given: Cost price of each T-shirt = $5.00
Amount required = $450
Total students = 75
Market price for each T-shirt to raise the required amount = (Amount required ) ÷ 75
= $450 ÷ 75
= $ 6
Mark up percent = 

Hence, Mark up percent = 20%