Step-by-step explanation:
4x2 - 25b2
We can solve it by the squares so
(2x - 5b) (2x + 5b)
2) x2 - 81
The same case is here so
(x - 9) (x + 9)
If his water to cement ratio is 20 to 30, this means that if he uses 20 liters of water, he'd use 30 liters of cement.
The total mixture would then be 20+30=50 liters.
and the water would be 20/50=0.4 or 40% of the total mixture.
Answer:
Step-by-step explanation:
So to do this, you would find the surface area of a box. Since it is a rectangular prism, two sides will always have the same area and so there are 3 different areas. 18*15*2 = 540 and 18*3*2 = 108 and 3*15*2 = 90 and 90 + 108 + 540 = 738 inches