Pls help me pls dont answer if you dont know

Answer:
the answer is 147
Step-by-step explanation:
first you do 3.5cm times 84cm which is 294cm
then you do 294cm divided by 2 which is 147cm
the reason why you divide by 2 is because parallelograms like the triangle can be also halved into 2 separate triangles!!
hope this helped <3