To multiply decimals, first multiply as if there is no decimal. Next, count the number of digits after the decimal in each factor. Finally, put the same number of digits behind the decimal in the product.

so.. check your "c" choices, to see which one gives you a positive discriminant
$24 for each student to go on the bus + $10 for lunch . $34 for each student .
By solving for x you get x=6