Chemistry and Chemical Reactivity (9th Edition)

$Z=18\ g/mol$ $A=26\ g/mol$
Molar masses: $A_2Z_3:\ 15.9\ g\div0.15\ mol=106\ g/mol$ $AZ_2:\ 9.3\ g\div0.15\ mol=62\ g/mol$ $62=A+2\times Z\rightarrow A=62-2\times Z$ $106=2\times A+3\times Z$ $106=2\times (62-2\times Z)+3\times Z$ $Z=18\ g/mol$ $A=26\ g/mol$