Question

At the library book sale, each type of book is priced differently. The table shown here lists the number of books that Joy and each of her friends bought. It also lists the amount that each person spent. Find the price of each type of book.

Answer 1

HELP PLEASE

Answer 2

I understand the problems Have you done simultaneous equations beforehand?

Answer 3

And, have you doin matrices before, @janettevegaa

Answer 4

NO I HAVEE NOT

Answer 5

Have you learnt simultaneous equations?

Answer 6

lol no

Answer 7

Oh, lol. Does this seem similar?
\[x+y-6\]\[2x-y=10\]?

Answer 8

okay ya that does

Answer 9

Ok, good. Now, we are going to have THREE of the variables, \(x, y, z\).
\[x =\text{Hard Cover Price}\]\[y =\text{Paperback Price}\]\[z =\text{Audio Book Price}\]

Answer 10

omg. :O! HOW DID YOU GET IT SO EQUAL?! did you cheat? xD

Answer 11

magic

Answer 12

h = hardcover
p = paperback
a = audio

3h + 4p + a = 17
2h + 5p + a = 15 <-- these are the 3 equations you will be using
3h + 3p + 2a = 20
=========================

3h + 4p + a = 17 --->(-1)
2h + 5p + a = 15
----------------
-3h - 4p - a = -17 (result of multiplying by -1)
2h + 5p + a = 15
----------------add
-h + p = -2

2h + 5p + a = 15 --->(-2)
3h + 3p + 2a = 20
----------------
-4h - 10p - 2a = -30 (result of multiplying by -2)
3h + 3p + 2a = 20
----------------add
-h - 7p = -10

-h + p = -2 --->(-1)
-h - 7p = -10
--------------
h - p = 2 (result of multiplying by -1)
-h - 7p = -10
--------------add
-8p = -8
p = 1

-h + p = -2
-h + 1 = -2
-h = -2 - 1
-h = -3
h = 3

3h + 4p + a = 17
3(3) + 4(1) + a = 17
9 + 4 + a = 17
13 + a = 17
a = 17 - 13
a = 4

check..
2h + 5p + a = 15
2(3) + 5(1) + 4 = 15
6 + 5 + 4 = 15
11 + 4 = 15
15 = 15 (correct)

hardcover books (h) cost $3
paperback books (p) cost $1
audio books (a) cost $4

Answer 13

im lost , very lost @Ahsome @dan815

Answer 14

Do you still need help, @janettevegaa?

Answer 15

read that solution from texas chic closely

Answer 16

i do but on something else @ahsome