let w = number of watches.
let p = number of pens.
w + p = 610
1/5 of the watches and 1/3 of the pens were from japan.
a total of 150 watches and pens were from japan.
1/5 * w + 1/3 * p = 150
these 2 equations need to be solved simultaneously.
leave the first equation as is and multiply both sides of the second equation by 5 to get:
w + p = 610
w + 5/3 * p = 750
subtract the first equation from the second to get:
2/3 * p = 140.
solve for p to get 210.
if w + p = 610, and p = 210, then w must be equal to 400.
you get w + p = 400 + 210 = 610.
you get 1/5 * w + 1/3 * p = 1/5 * 400 + 1/3 * 210 = 80 + 70 = 150.
this confirms that the solutions are correct because the original equations are both true when w = 400 and p = 210.
you were asked:
how many watches in the box?
how many pens from Korea?
since w = the number of watches, then the number of watches in the box = 400.
since p = the number of pens in the box, and since 1/3 of the pens in the box were from japan, then 2/3 of the pens in the box were from korea.
2/3 * p = 2/3 * 210 = 140.
your solution is:
the number of watches in the box was 400.
the number of pens in the box from korea was 140.
if you drew a table of what was in the box, it would look something like this:
watches pens total
japan 80 70 150
korea 320 140 460
total 400 210 610