She can buy a maximum of 12 books for her music class
Answer: ![4r + 5(20-r) \le 92](https://tex.z-dn.net/?f=4r%20%2B%205%2820-r%29%20%5Cle%2092)
=======================================
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,
![4r + 5(20-r) \le 92](https://tex.z-dn.net/?f=4r%20%2B%205%2820-r%29%20%5Cle%2092)
--------------------
Extra info:
If you want to solve for r, then
![4r + 5(20-r) \le 92](https://tex.z-dn.net/?f=4r%20%2B%205%2820-r%29%20%5Cle%2092)
distribute
![100 - r \le 92](https://tex.z-dn.net/?f=100%20-%20r%20%5Cle%2092)
add r to both sides
![100 \le 92+r](https://tex.z-dn.net/?f=100%20%5Cle%2092%2Br)
subtract 92 from both sides
![8 \le r](https://tex.z-dn.net/?f=8%20%5Cle%20r)
![r \ge 8](https://tex.z-dn.net/?f=r%20%5Cge%208)
So John must buy at least 8 red pens. The most he can buy is 20 red pens since he wants 20 pens total.
Answer: 26
Step-by-step explanation:
Let the tens digit=x
and units digit=y
Hence sum x+y=8…………(i)
Number =10x+y
Number formed by reversing the digits =10y+x
(10y+x)=(10x+y)+36 i . e. 9y-9x=36
Or y=x+4…………..(ii)
Adding (i) and (ii) gives 2y=12
Hence y=6
hence from (i)
x=8-y
8–6 = 2
hence Number =26
Answer:
56 with re9
Step-by-step explanation make a square on a paper make 3 line on top of each line put 800 40 and 9 on the side put 15 search up 15 dived by 800 and 40 dived by 15 then 9 add it all up the yo go give me brainlist
Answer:
1 Foot = 304.8 Millimeters
Step-by-step explanation:
:/