A store sells black ink pens for $5 and red ink pens for $4. John wishes to buy 20 pens but doesn’t wish to spend more than $92. Writing r for the number of red pens, form an inequality to show this information

=======================================

Explanation:

r = number of red pens

4r = cost of buying r red pens

example: if r = 10, then 4r = 4*10 = 40 is the total cost of buying 10 red pens

If John buys r red pens, then he must buy 20-r black pens so that r and 20-r add to 20.

John buys 20-r black pens, and at $5 each, so it will cost 5(20-r) dollars for just the black pens alone.

In total, John spends 4r + 5(20-r) dollars for all the pens (red & black)

We want $92 be the most he spends. This is the ceiling or highest value possible.

Therefore,

--------------------

Extra info:

If you want to solve for r, then

distribute

add r to both sides

subtract 92 from both sides

So John must buy at least 8 red pens. The most he can buy is 20 red pens since he wants 20 pens total.

236 cm 16 time 12 = 192

6 times 7 = 42

192+42