The balance of Ian's investment account can be modeled with the function f(t)=1000\cdot e^{(0.08t)}f(t)=1000⋅e (0.08t) f, left parenthesis, t, right parenthesis, equals, 1000, dot, e, start superscript, left parenthesis, 0, point, 08, t, right parenthesis, end superscript, where ttt is the number of years since he opened the account. Here is the graph of fff.

If triangle ABC is congruent to triangle DEF, their interior angles are congruent, because congruent parts of congruent triangles are congruent (CPCTC).

That means ∠D is congruent to ∠A; ∠D is equal to 8x - 2.

Interior angles of all triangles add to equal 180 degrees, so you can set the sum of these interior angle values equal to 180 and solve for x.

180 = (8x - 2) + 22 + 72

180 = 8x - 2 + 22 + 72

180 = 8x + 92

88 = 8x

11 = x

x = 11