Let S be the set of ordered triples (x,y,z) of real number for which log10(x+y)=z and log10(x²+y²)=z+1. If a,b are real number such that for all ordered triplets (x,y,z) in S, we have x³+y³ =a.10³ˣ+b.1²ˣ. Then thevalue of 9a+b) is
a) 15
b) 152
c) 29/2
d) 39/2