Let x be the price for 1 pound of tin, in dollars; then the price for 1 pound of copper is (x-1) dollars. The total cost is the sum of costs of ingredients. 4x + 6*(x-1) = (4+6)*4.15 Simplify and solve 10x = 10*4.15 + 6 10x = 47.50 x == 4.75. ANSWER. A pound of tin is worth $4.75. CHECK. The total cost of ingredients is 4*4.75 + 6*(4.75-1) = 41.50 dollars, same as the total cost of the alloy 4.15*(4+6) = 41.50 dollars. ! Correct !