Question 130917
Let x=number of American
Let y=number of British
Let z=number of comics

Now we know that
10x+5y+0.5z=100-----------------eq 1
we also know that:

x+y+z=100-----------------------eq 2

Two equations in three unknowns means that we need to do some smart guessing.

First, multiply eq1 by 2 and then subtract eq2 from it.
20x+10y+z=200 minus x+y+z=100 equals:

19x+9y=100  subtract 9y from each side
19x=100-9y  divide each side by 19

x=((100-9y)/19)---------------EQ3

Now we have a relation between the number of American magazines and the number of British magazines and here is where we do some smart figuring:

First, we cannot have a fraction of a magazine (our answers have to be whole numbers)

And secondly, we cannot have negative magazines.

Armed with this information, lets take a look at EQ3

We can see that y cannot be greater than 11 lest we have negative American magazines.  So lets set up a table and see what we have

If y=1; x=91/19-----------------NO GOOD ---FRACTION OF MAG
If y=2; x=82/19-------------------NO GOOD----FRACTION OF MAG
If y=3; x=73/19---------------------NO GOOD---FRACTION OF MAG
If y=4;  x=64/19------------------------NO GOOD----FRACTION OF MAG
If y=5; x=55/19----------------------NO GOOD---FRACTION OF MAG
If y=6;  x=46/19-----------------------NO GOOD----FRACTION OF MAG
If y=7; x=37/19-------------------------NO GOOD---------FRACTION OF MAG
If y=8;  x=28/19--------------------------NO GOOD--FRACTION OF MAG
If y=9;  x=19/19=1---------------------BINGO!!!!!
If y=10; x=10/19----------------------------------NO GOOD---FRACTION OF MAG
If y=11;  x=1/19------------------------------NO GOOD---FRACTION OF MAG

So our only possibilities are:
x= # of American Magazines=1
y=# British Magazines=9
Then z=# of comics would have to equal=90

CK
1+9+90=100
100=100
9*5+1*10+90*0.5=100
100=100

Hope this helps---ptaylor