Answer:
The red pens are 168.
Explanation:
Given:
In a box of pens, 2/7 of them are red. of the remaining pens 1/6 of them are blue and the rest are black. there are 280 more black pens than blue pens.
Now, to find the red pens in the box.
Let the total pens be
.
Red pens be

Remaining pens =

So, blue pens =

Now, black pens =
-(blue +red)
Black pens =

According to question:
Black pens = Blue pens + 280






On solving we get:

So, red pens =

=
.
Therefore, the red pens are 168.