Hello from MrBillDoesMath!
Answer:
z = 28 (y/x)
Discussion:
" z varies inversely with x and directly with y" translates into
z = k * (y/x) (*)
Substituting x = 2, y = 3, z = 42 in (*) gives
42 = k (3/2) => multiply both sides by 2/3
42 (2/3) = k (3/2)(2/3) => 42(2/3) = 28; (3/2)(2/3) = 1
28 = k
Conclusion:
z = 28 (y/x)
Thank you,
MrB