Let,
x = kg of pure 100% tin
and y = kg of 4% tin
x + y = 32
x = 32 -y
1.00 x + 0.04 y = 0.16 x 32
By solving the above system of equations we find:
Now put the value of x in the above equation;
1 x (32 - y) + 0.04 y = 5.12
32 – y + 0.04y = 5.12
y – 0.04y = 32 – 5.12
0.96y = 26.88
y = 26.88/0.96
y = 28 kg of 4% tin
Now put the value of y in x = 32 – y
x = 32 – 28
x = 4 kg of pure 100% tin