A letter other than x becomes a slider. Rewrite the equation in terms of x, or the graph will not draw. Desmos access is in Desmos on the ACT.
t, n, and theta are not x
Replace the other letter with x, or type x = the expression if the item already solved for y. Sliders themselves are in sliders on the ACT. If you meant to keep both x and y, graph both, in if you see x and y.
Domain restrictions still use braces after the equation, in domain restrictions.
The bottom line
Non-x letters make sliders. Rename the variable before you graph.
Start practicing
Start with a free diagnostic, then drill your weak spots with 15-question quizzes and track how you're doing across Reading, English, and Math. Compare plans whenever you're ready to go further.
This article offers general ACT prep guidance. The ACT can change from year to year, including its format, scoring, policies, test dates, and fees, so always confirm the latest details on the official ACT website at act.org before you make decisions. ACT® is a registered trademark of ACT, Inc. thirty-six is not affiliated with, endorsed by, or sponsored by ACT.