 \frac{ a }{b } 

 \frac{ c }{d } 

 \frac{ a }{b } +  \frac{ c }{d } 

a = 1 (slider from 1 to 10, step 1)
b = 1 (slider from 1 to 10, step 1)
c = 2 (slider from 1 to 10, step 1)
d = 1 (slider from 1 to 10, step 1)
W: (a / b, 0)
Y: (c / d, 0)
Z: (a / b + c / d, 0)