what is 15 over 12 multiplied by 5 multiplied by 1 and 1 over 2?

15/12 x 5 x 1 x 1/2

=  15/12 x 5/1 x 1/1 x 1/2

Multiplying all the numerators together and all the denominators together:

=  75/24

Simplifying (dividing both the numerator and denominator by 3):

=  25/8