The normal price of each chair is
![=\text{ \$15}](https://img.qammunity.org/2023/formulas/mathematics/high-school/5cf7leeifdlgew3s539mse1cjh5int2qm8.png)
The percentage off the normal price is
![=89.5\text{ \%}](https://img.qammunity.org/2023/formulas/mathematics/high-school/tc7wyaid0s8r6jpb2ct6dxn12vislz5i2p.png)
The percentage of the present price of each chair will be
![\begin{gathered} 100\text{ \% - 89.5 \%} \\ =10.5\text{ \%} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/18th2ybrtk4crjf0rbde6euhtfqx2217zw.png)
To calculate the present value of one chair, we will use the formula below
![=\text{percentag of the normal price}* normal\text{ price}](https://img.qammunity.org/2023/formulas/mathematics/high-school/f4ao3uwj2yflws5ysnx363o6s2v6b7l3gg.png)
By substituting the values, we will have
![\begin{gathered} \text{new price of each chair will be=}(10.5)/(100)*15 \\ \text{new price of each chair will be}=(157.5)/(100) \\ \text{new price of each chair will be}=\text{ \$1.575} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/acvkhry141jw6noxkojhlasj02yqf8v8my.png)
Since Mr .Krabs bought 4 chairs, the amount he spent will be
![\text{Amount spent = price of each chair}* Number\text{ of chairs}](https://img.qammunity.org/2023/formulas/mathematics/high-school/1izbkv8zu86dfs01mkg6mi1ighvavbmpye.png)
By substituting the values, we will have
![\begin{gathered} \text{Amount spent = price of each chair}* Number\text{ of chairs} \\ \text{Amount spent}=1.575*4 \\ \text{Amount spent}=\text{ \$6.30} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/97budhvu8km5s71ciywv35xkaqy451zzjd.png)
Therefore,
The amount Mr.Krabs spent is = $6.30