2/5 guests are men. there are 3 times as many women as kids. there are 45 more men than kids. how many in all?

I know that if 2/5 of the guests are men then the total guests should equal 5/5.

You can use x to represent the number of kids.

If there are 45 more men than kids you'd get men =x+45

So that would also mean that 2/5 = x+45

Women would be 3x

women and kids would have to equal the 3/5 missing from the 5/5

...but I keep coming up with a decimal...

if you avoid the 2/5 as unimportant information you can just do the math for the rest and come up with 9 kids, 27 women, and 54 men.  But plugging that back into the 2/5 doesn't come out right. Are you sure these are the numbers?