Example of an algebraic expression that always has the same value regardless of the value of the variable

If tan2a=cot(a+60), find the value of a, where 2a is an acute angle

One cell phone plan charges $20 per month plus $0.15 per minute used. a second cell phone plan charges $35 per month plus $0.10 per minute used. write and solve an equation to find the number of minutes you must talk to have the same cost for both calling plans.

Use the equation and type the ordered-pairs. y = 2 ^x