i need help witht the following problem-

A merchant mixed 10 lb of cinnamon tea with 5 lb of spice tea. The 15-pound mixture cost

$40. A second mixture included 12 lb of the cinnamon tea and 8 lb of the spice tea. The 20-

pound mixture cost $54. Find the cost per pound of the cinnamon tea and of the spice tea.

thanks!