Given:
The carpenter spent 7/8 of his money on bags of sand for the sandbox.
Let the amount that carpenter having be 'x'
[tex]\text{amount spent on bags of sand=}\frac{7}{8}x[/tex][tex]\text{Amount spent on decoration= }\frac{1}{16}x[/tex][tex]x-\frac{7x}{8}-\frac{x}{16}=19.90[/tex][tex]\frac{16x-14x-x}{16}=19.90[/tex][tex]x=19.90\times16[/tex][tex]x=318.40[/tex]The money carpenter start with $318.40