PLZ Help with 3 Test Questions

PLEASE HELP! would be much appreciated : )

1. For any real numbers x, let $ x be defined as the greatest integer less than or equal to x.

What is $ -1.5 + $ 4.5 ?

2. For any integers n, let ® n be defined as the sum of the distinct prime factors of n. For instance, ® 36=5, because 2 and 3 are the only prime factors of 36 and

2+3=5.

What is the smallest value of w for which ® w=12 ?

3. For all real numbers a and b, let the expression a http://www.mrslonline.com/pix/s/approve.gif b be defined by the equation a http://www.mrslonline.com/pix/s/approve.gif b= 10a + b.

If 2.5 http://www.mrslonline.com/pix/s/approve.gif y = 50, what is the value of x?

Thank you very much