Express the fractions 1/2, 3/16, and 7/8 with an LCD.

LCD stands for the least common denominator. 
The least common multiple of the denominators can be calculated as follows;
denominators are 2,16 and 8
divide all by 2      2/2 = 1       16/2 = 8        8/2 = 4
Divide by 2                    1        8/2 = 4         4/2 = 2
Divide by 2                    1        4/2 = 2         2/2 = 1
Divide by 2                     1        2/2 = 1           1
multiply - 2x2x2x2 = 16
16 is the least common multiple of 2,16 and 18
[tex] \frac{1}{2} [/tex]  multiply both by 8 - [tex] \frac{8}{16} [/tex]
[tex] \frac{3}{16} [/tex] as it is
[tex] \frac{7}{8} [/tex] multiply both by 2  - [tex] \frac{14}{16} [/tex]
answer is 8/16,3/16,14/16