Question 755319
A sandwich is served on a 18 inch bun. 
Jenny, Demi, and Sarah agree to share the sandwich. Due to different appetites 
Jenny cuts the sandwich in a way that Demi gets half of what Jenny gets and Sarah gets three-fourths of what Jenny gets. 
Find the length of each person's sandwich. 

let x be Jenny's length of sandwhich, then

x + x(1/2) + (3/4)x = 18

(4/4)x + (2/4)x + (3/4)x = 18      (convert all fractions to a common denominator)

(9/4)x = 18                       (combine fractions)

9x = 72                        (multiply both sides of = by 4)

x = 8

Jenny's sandwich is 8 inches
Demi's sandwich is 4 inches     (1/2 of Jenny's)
Sarah's sandwich is 6 inches    (3/4 of Jenny's)