In Example 6, change 5 parts tin to 7 parts tin.

Data from Example 6

An alloy is 5 parts tin and 3 parts lead. How many grams of each are in 40 g of the alloy? First, let x = the number of grams of tin in the 40 g of the alloy. Next, we note that there are 8 total parts of alloy, of which 5 are tin. Thus, 5 is to 8 as x is to 40. Therefore,

There are 25 g of tin and 15 g of lead. The ratio 25/15 is the same as 5/3.

parts tin total parts in 100 5 8 40 40() = x = 401 grams of tin total grams 25 g