Area of a triangle = 1/2 × base × height
Plug in what we know.
78 = 1/2 × b × 9¾
Multilply each side by 2 to get rid of the 1/2...
156 = b × 9¾
Write 9¾ as an improper fraction.
(9¾ = 9 + 3/4 = (9×4)/4 + 3/4 = 36/4 + 3/4 = 39/4)
156 = b × 39/4
Multiply each side by 4...
624 = b × 39
Divide each side by 39...
16 = b
Done! The length of the base of the triangle is 16 inches.
