I need help, im a single dad construction worker from los angeles, my daughter is a very smart person. Im having trouble correcting a wrong answer in math. She goes to Kumon academy for math and reading, but this problem im out of words

Answer:
B=210
C=450
Step-by-step explanation:
Since you are asking for number 8, let's work with that problem :)
Firstly, we have to know we have rectangles here, and the area of a rectangle is given by the following formula:
[tex]A_{rectangle}=(width)(height)[/tex]
So, in this problem we are given as an example the rectangle [tex]A[/tex], with witdth [tex]90[/tex] and height [tex]30[/tex]. So, its area is:
[tex]A=(90)(30)=2700[/tex]
The same happens with the small rectangle [tex]B[/tex]:
[tex]B=(7)(5)=35[/tex]
And, we have to do the same with rectangles [tex]B[/tex] and [tex]C[/tex]:
Rectangle [tex]B[/tex]:
Width:7
Height:30
[tex]B=(7)(30)=210[/tex]
Rectangle [tex]C[/tex]:
Width:90
Height:5
[tex]B=(90)(5)=450[/tex]
If we sum [tex]A[/tex], [tex]B[/tex], [tex]C[/tex] and [tex]D[/tex] the result must be equal to the total are of the big rectangle:
[tex]A+B+C+D=2700+210+450+35=3395[/tex]
Area of big rectangle with width [tex]90+7=97[/tex] and height [tex]30+5=35[/tex]:
[tex](97)(35)=3395[/tex]