How many ways can you make a 3-letter arrangements out of the letters in the word trapezoid?

You can make 81 words from 3-letter arrangements out of the letters in trapezoid.

3-LETTER ARRANGEMENTS:

Ado, adz, aid, air, ait, ape, apo, apt, are, art, ate, azo, dap, dei, die, dip, dit, doe, dor, dot, ear, eat, era, eta, ire, oar, oat, oda, ode, ope, opt, ora, ore, ort, pad, par, pat, pea, ped, per, pet, pia, pie, pit, pod, poi, pot, pro, rad, rai, rap, rat, red, rei, rep, ret, rai, rid, rip, rod, roe, rot, tad, tae, tao, tap, tar, tea, ted, tie, tip, tod, toe, top, tor, zap, zed, zep, zip, zit, zoa