Question

A friend bought cookbooks and travel books at a book sale. She spent $52 and bought 7 books. The cookbooks cost $6 apiece and the travel books cost $8 apiece. How many cookbooks did the friend buy? Remember No Units, just the answer

Answer 1

Answer:

2

Step-by-step explanation:

$52

7books

$6 CB which means she brought 2 which is $12

$8 TB and then 7-2 because he already brought 2 CB so that means that he brought 5TB which is 40

Then add 40 +12 = $52 for 7 books

Answer 2

Answer:

2 cookbooks

Step-by-step explanation:

soln:

let cookbooks be x and travel books be y then,

the given equations are as follows:

x+y=7...eqn(i)

6x+8y=52

or,6x+8y-52=0

or,2(3x+4y-26)=0

or,3x+4y-26=0

or,3x+4y=26... eqn(ii)

comparing the equation with standard form, we have,

coef of x coef of y constant term

1 1 7

3 4 26

D = | 1 1 | = 1*4-3*1 = 4-3 = 1

3 4

D1 = | 7 1 | = 7*4-26*1 = 28-26 = 2

26 4

D2 = | 1 7 | = 1*26-3*7 = 26-21 = 5

3 26

using cramer's rule,

x = D1/D = 2/1 = 2

y = D2/D = 5/1 = 5

hence, he/she bought 2 cookbooks.