Perform the indicated calculations graphically for the following three mixtures. Use a triangular diagram with xa on the horizontal axis and xc on the vertical axis.

Q: 2000 lb: xa = 0.7, xb = 0.2, xc = 0.1.

R: 1000 lb: xa = 0.3, xb = 0.5, xc = 0.2.

S: 3000 lb: xa = 0.1, xb = 0.2, xc = 0.7.

a.) Add Q, R and S.

b.) Add Q to S, then subtract R.

c.) Subtract R from S, then add Q.

d.) Subtract R from Q, then add S.