An alloy weighing 30 lbs. is 11% tin. the alloy was made by mixing a 15% tin alloy and a 9% tin alloy. how many pounds of each alloy were used to make the 11% alloy? lbs. of the 15% alloy and lbs. of the 9% alloy.

We let x = pounds of alloy that is 15% tin

The problem is modeled by the equation:

0.11(30) = 0.15x + 0.09(30-x)

The equation means that the amount of tin does not change. Also, the amount of alloy (total weight - weight of 15% alloy) is (30-x).  

Solving for x:

3.3 = 0.15x +2.7 - 0.09x

.06x = 0.6

x = 10 lbs

30-10 = 20 lbs

10 lbs. of the 15% alloy and 20 lbs. of the 9% alloy

step-by-step explanation: