Afather is 3 times as old as his son. fifteen years ago, the father was 9 times as old as his son was then. find their present ages.

What are “like terms”? why can we only add like terms?

Suppose i flip two identical coins. what is the probability that i get one head and one tail?

In the figure below, ∠dec ≅ ∠dce, ∠b ≅ ∠f, and segment df is congruent to segment bd. point c is the point of intersection between segment ag and segment bd, while point e is the point of intersection between segment ag and segment df. the figure shows a polygon comprised of three triangles, abc, dec, and gfe. prove δabc ≅ δgfe.