Math Problem (Level 1) : Overlapped two triangles (J2)

△DBE and △ABC are overlapped as shown in the figure below.
AB : DB = 7 : 3 and BC : BE = 8 : 5. The area of △DBE is 15 cm². 

Find the area of △ABC. 

Answer

56 cm²

Solution

The area ratio of △ABC and △DBE is set to (7 × 8) : (3 × 5) = 56 : 15.
Since △DBE is 15 cm², △ABC is 15 × (56/15) = 56 cm².