Question

At the shopping mall, Joaquin bought 4 pretzels and a bottle of water for $11.50. Kelly bought 3 pretzels and a bottle of water for $9.00. What is the price of a bottle of water?

Answer 1

Water: `color(green)($1.50)`

Explanation:

Let `P` be the price of a pretzel
and `W` be the price of a bottle of water.

We are told
[1]`color(white)("XXX")4P + 1W = 11.50`
[2]`color(white)("XXX")3P + 1W =9.00`

Subtracting [2] from [1] we get
[3]`color(white)("XXX")1P =2.50`

Substituting `2.50` for `P` in [1], we get
[4]`color(white)("XXX")4xx2.50+1W=11.50`
or
[5]`color(white)("XXX")1W=1.50`

Answer 2

The price of a bottle of water is 5.50$

Explanation:

The price of one pretzel is x$.

The price of one water bottle is y$.

4x+y=11.50
3x+y=9.00

subtract the second equation from first

The price of a bottle of water is 5.50$