Kevin sold a box of 28 books at a yard sale for a total of $54.64. he sold the paperback books for $1.68 each and sold the hardcover books for $2.44 each. which system of equations can be used to determine the number of $1.68 paperback books, x, and the number of $2.44 hardcover books, y, that were sold at the yard sale?

a.
x + y = 28
1.68x + 2.44y = 54.64

b.
2.44x - 1.68y = 28
x + y = 54.64

c.
x + y = 28
2.44y = -1.68x + 54.64

d.
y = x - 54.64
1.68x + 2.44y = 28

A.  

x + y = 28

1.68x + 2.44y = 54.64

Step-by-step explanation:

Let x = paperback books and y = hardback books

x+y =28

We know that paperbacks cost 1.68 and hardback cost 2.44

1.68x + 2.44y = 54.64

We have 2 equations and 2 unknowns

x+y =28

1.68x + 2.44y = 54.64

step-by-step explanation:

the first 5 right here the next 5 i will upload as separate question

geometry: triangles

solvers

lessons

answers archive

call the larger triangle abc

then the smaller triangle cde is similar to abc (all angles are equal, aaa).  

ab is the side that is 36, and we wish to find de, the side corresponding to ab

area_cde = area_abc - area_cde --> area_abc / area_cde = 2

let x=length of de

ratio of areas = (ratio of sides)^2

+2+=+%2836%2fx%29%5e2+

+2+=+1296%2fx%5e2+

++x%5e2+=+1296%2f2+=+648+

25.45584