Probably the last one
Use the equation for the area of a triangle 1/2(bxh)
Then multiply that number by 2 to get the area of the complete shape.
I believe it's the first 3 boxes
Im thinking 10 because 10+40=50 and 10x7=70
Answer:
6.71
You use pythagoras so you do:
6² + 3² = 45
square root 45 =6.71