What is the sum of the next two terms in the sequence -3, -1, 3, 9,

First we have to figure out what the next 2 terms are, ya reckon ?

Look at the terms we have:

From the 1st to the 2nd term . . . add 2
From the 2nd to the 3rd term. . . add 4
From the 3rd to the 4th term . . . add 6
From the 4th to the 5th term . . . add 8

So there's the pattern we want.

To get the next term,          we add  10  to 17, and get  27.
And for the one after that, we add  12  to 27, and get 39 .

To answer the question, the sum of (27 + 39) is  66 .

It's like discovering the answer to a puzzle. the purpose in solving an equation is to find the value or values of the variable that makes it a true statement. any value of the variable that makes the equation true is called a solution to the equation.