Question

If 6 notebooks and 4 thumb drives costs 33.2 and 5 notebooks and 5 thumb drives costs 35.75 what is the cost of each item

Answer 1

The cost of each notebook is $ 2.3 and cost of each thumb drive is $ 4.85

Solution:

Let "a" be the cost of each notebook

Let "b" be the cost of each thumb drive

Given that,

6 notebooks and 4 thumb drives costs 33.2

Therefore,

6 notebook x cost of each notebook + 4 thumb drive x cost of each thumb drive = 33.2

`6 * a + 4 * b = 33.2`

6a + 4b = 33.2 ----------- eqn 1

5 notebooks and 5 thumb drives costs 35.75

5 notebook x cost of each notebook + 5 thumbdrive x cost of each thumb drive = 35.75

`5 * a + 5 * b = 35.75`

5a + 5b = 35.75 --------- eqn 2

Let us solve eqn 1 and eqn 2

Multiply eqn 1 by 5

30a + 20b = 166 ----------- eqn 3

Multiply eqn 2 by 6

30a + 30b = 214.5 ---------- eqn 4

Subtract eqn 3 from eqn 4

30a + 30b = 214.5

30a + 20b = 166

( - ) -----------------

10b = 48.5

Divide both sides by 10

b = 4.85

Subtsitute b = 4.85 in eqn 1

6a + 4(4.85) = 33.2

6a + 19.4 = 33.2

6a = 13.8

Divide both sides by 6

a = 2.3

Thus cost of each notebook is $ 2.3 and cost of each thumb drive is $ 4.85