Answer :
The normal price of each chair is
[tex]=\text{ \$15}[/tex]The percentage off the normal price is
[tex]=89.5\text{ \%}[/tex]The percentage of the present price of each chair will be
[tex]\begin{gathered} 100\text{ \% - 89.5 \%} \\ =10.5\text{ \%} \end{gathered}[/tex]To calculate the present value of one chair, we will use the formula below
[tex]=\text{percentag of the normal price}\times normal\text{ price}[/tex]By substituting the values, we will have
[tex]\begin{gathered} \text{new price of each chair will be=}\frac{10.5}{100}\times15 \\ \text{new price of each chair will be}=\frac{157.5}{100} \\ \text{new price of each chair will be}=\text{ \$1.575} \end{gathered}[/tex]Since Mr .Krabs bought 4 chairs, the amount he spent will be
[tex]\text{Amount spent = price of each chair}\times Number\text{ of chairs}[/tex]By substituting the values, we will have
[tex]\begin{gathered} \text{Amount spent = price of each chair}\times Number\text{ of chairs} \\ \text{Amount spent}=1.575\times4 \\ \text{Amount spent}=\text{ \$6.30} \end{gathered}[/tex]Therefore,
The amount Mr.Krabs spent is = $6.30