The least common multiple means that the least multiple that the numbers have in common. So you can make a little chart with each of the numbers multiples like so.. 3,6,9,12,15,18,21,24,27,30,33,36,39,42,45,48,51,54,57,60,63,66,69, (Just added 3 each time) 5,10,15,20,25,30,35,40,45,50,55,60,65,70, (Just added 5 each time) 7,14,21,28,35,42,49,56,63,70,77 (Just added 7 each time) No we can go and look through the multiples and see what number they all have that's the same! You might have to keep added on multiples until you find some that are alike! You'll eventually reach 105 for each of the numbers and see that that's the first one that they have that's the same!! So 105 would be your least common multiple!
Since you are subtracting 11 on the side with the variable, you have to add it on the other side. 17+11=28. Then, to solve the problem you are left with, 7c=28. You are multiplying on the side of the variable, so you divide 28 by 7. Your answer to the problem is C=4 i hope this helps
