there are 84 black blue and red pens altogether in a bag . there are 6 times as many blue pens as red pens . there are 4 more black pens than red pens. how many black pens are there?

Answer 1

let the number of red pens be x
(I defined the red pens because they were mentioned in both condition cases)

<there are 6 times as many blue pens as red pens> ------> number of blues = 6x
<there are 4 more black pens than red pens> ----> number of blacks = x + 4

total = 84
x + 6x + x+4 = 84

now it is easy, solve for x, then calculate x+4

Answer 2

X red pens.
6x blue pens.
x+4 black pens.

x + 6x + x+4 = 84
X =
x+4 =

Answer 3

X=74