B and D because there are the reverse of 67 + 38 = 105.
Hope that helps :)
Let's write an inequality, such as follows: x < sqrt(50) < y. Square both sides of the equation. We get x^2 < 50 < y^2. Obviously, x is between 7 and 8. Also notice, that for integers a,b, (ab)^2/b^2, equals a^2. So let's try values, like 7.1. Using the previous fact, (7.1)^2, equals (71)^2/100. So, (7.1)^2, equals 50.41. Thus, our number is between 7 and 7.1. We find, with a bit of experimentation, that the square root of 50, is 7.07.
15 x 100= 1500 centimeters
1/3 + 1/3 + 1/3 + 1/3 + 1/3 + 1/3 = 6/3
