Atotal of 642 tickets were sold for the school play. they were either adult tickets or student tickets. there were 58 fewer student tickets sold than adult tickets. how many adult tickets were sold?

Let a = adult tickets, s = student tickets. We are going to use these to set up a system of equations. 

a + s = 642
a - s = 58

Now we combine like terms. The s variables cancel out:

2a = 700
a = 350

Now we plug back in.

350 + s = 642

Subtract 350 from both sides.

s = 292

There were 350 adult tickets sold and 292 student tickets sold.