The area of a triangle is 80 cm². If its base is 8 cm and its height is (6+k) cm, find the value of k.

Look at the picture.

Area triangle = base × height ÷ 2
80 = 8 × (6 + k) ÷ 2
80 = 4 × (6 + k)
(6 + k) = 80 ÷ 4
6 + k = 20
k = 20 - 6
k = 14