-0.272727272727272727272727272727
Answer:
x = -1, x = 1
Step-by-step explanation:
Factor the equation. (It's a difference of squares, so we know the form will be (a-b)(a+b).)

Test this by FOILing it out, if you're unsure. This is something it can be good to memorize!
Set it equal to 0.

Separate the two parenthetical expressions by the Zero Product Property.

Solve for x!

The base is a square, therefore all the sides of the base are the same. This also means all the triangles have the same area.
10*10 = 100 cm^2 for the base
0.5*10*12 = 60 cm^2 for each triangle
100 + 4(60) = 340 cm^2
take x =initial deposit amount. then make equation:
x+75.5+55.25-25.15-18.65 = 210.85
simplify:
x+86.95 = 210.85
x=210.85 - 86.95
x=123.90
so Initial deposit amount is $123.90
check: 210.85+18.65+25.15-55.25-75.5 = 123.9
123.9 = 123.9