Em uma biblioteca existem 25 prateleiras com 65 livros em cada uma quantos livros tem nessa biblioteca

x - 3y = 6 and x + y = 110 represents the system of equations used to find x, the number of CDs she sold last week, and y, the number of CDs she sold this week

number of CDs Kitts sold last week "x" is 84 and number of CDs she sold this week "y" is 26

Let "x" be the number of CDs Kitts sold last week

Let "y" be the number of CDs she sold this week

Given that Last week she sold 6 more than 3 times the number of CDs that she sold this week

Number of CDs Kitts sold last week = 6 + 3(number of CDs that she sold this week)

x = 6 + 3y eqn 1

x - 3y = 6 eqn 2

Given that Ms. Kitts sold a total of 110 CDs over the 2 weeks

Number of CDs Kitts sold last week + number of CDs she sold this week = 110

x + y = 110 eqn 3

Thus eqn 2 and eqn 3 represents the system of equations used to find x, the number of CDs she sold last week, and y, the number of CDs she sold this week

Let us solve the above equations to find values of "x" and "y"

Substitute eqn 1 in eqn 3

6 + 3y + y = 110

6 + 4y = 110

4y = 104

From eqn 3,

x + 26 = 110

x = 110 - 26 = 84

Thus number of CDs Kitts sold last week = x = 84

Number of CDs she sold this week = y = 26