The lowest number that both 15 and 25 go into is 75. 15 goes into 75 5 times, and 25 goes into 75 three times.
55 goes into 20, 4 times.5 goes into 75, 15 times.
A percentage is really just the numerator (top number of a fraction) of a fraction for which the denominator (the bottom number of a fraction) is 100. So, for example 50% is the same as 50/100. Your question then comes down to "how do I change 21/75 to something over a hundred?"We'll call the "something "N". Then you set the two eqtions as equal; 21/75 = N/100. next multiply both sides of the equation times 100; 100 x 21/75= 100 x N/100. That causes the /100 on the right side to drop out and leaves 2100/75=N. Since 75 goes into 2100 exactly 28 times (2100/75=28) that means that N=28, so your answer is 28%. you can do a rough check of this by noting that 21/75 is a little less than one third and that 28% is also a little less than one third (33.3%).
3 is the hcf
The number 24 goes into 75 about 3.125 times.
GCF(36, 75) = 3 so the answer is 1 and 3
The only number that can divide by both 83 and 75 is one as 83 is a prime number and therefore only has 2 numbers that can divide by it anyway
One will go into both numbers evenly
25
1 and 5
1, 3, 5 and 15
1, 3, 5, 15.