Question

Kawan buy some protein bars at $0.90 and each water bottle cost $0.70 for each group hike he buys twice as many bottles of water as protein bars if he spends $46 in total how many bottles of water and protein bars does he buy?

Answer 1

Bottles of water: 40

Protein Bars: 20

Step-by-step explanation:

If we call

B = number of protein Bars

W = number of Water bottles

Since each B costs $0.9, each W costs $0.7 and the total spend is $46

We can write the equation:

`0.9B+0.7W=46`

Because, the total of $46 is equal to the number of W times the price, plus the number of B times the price.

We also know that there are twice as many W as B, we can write:

`2B=W`

We have these two equations:

`\begin{cases}0.9B+0.7W={46} \\ 2B={W}\end{cases}`

We can substitute the second equation in the first one:

`0.9B+0.7W=46\Rightarrow0.9B+0.7(2B)=46`

Now we can solve:

`\begin{gathered} \begin{equation*} 0.9B+0.7(2B)=46 \end{equation*} \\ 0.9B+1.4B=46 \\ 2.3B=46 \\ . \\ B=(46)/(2.3)=20 \end{gathered}`

B = 20, means that the amount of protein bars bought is 20.

Now, since there are twice as many bottles of water as protein bars:

`2\cdot20=40`

There are 40 water bottles and 20 protein bars