Im in fifth grade too. that was on my homework it confused me so much
Answer:
y = 3x -13
Step-by-step explanation:
y = 3x + 7
-1 = 3(4) + b
-1 = 12 + b
-13 = b
y = 3x -13
Well... Basically, you should prove this by SSS property(side-side-side). It's fair to say that the length of a side is equal to itself so The line that cuts through the rectangle is a side for both rectangles. Thus because of the given, all the sides of the triangles are equal to one another. This is a very important trick for geometry(I remember using it a lot).
Hope this helps!
1. Box off the squares (which you did)
2. Solve the area of the squares: (10cm x 10cm = 100cm each square)
3. Solve the area of the rectangle that is left: (you would do 40cm x 10cm since the other 10cm went with the square. The rectangle should end up to be 400cm.
4. Add the areas: 100cm + 100cm +400cm = 600cm
600cm is the answer