MATH
posted by cathy .
CASHEWS $8.00 PER KILOGRAM AND PECANS $9.00 PER KILOGRAM, HOW MANY KILOGRAMS OF EACH TO MAKE 10 KILOGRAMS THAT COST $8.40

x= # kg of cashews
10x = # kg of pecans
($8)(x) + ($9)(10x) = $8.40
here's a similar problem:
http://www.calculatorsoup.com/calculators/wordproblems/algebrawordproblem1.php