Find the variable x in the figure if ab ll cd ll ef where c and d are the midpoints of ae and bf.

CD is called the middle base and is equal to :(AB + EF)/2

CD = (AB + EF)/2

4x = [(x²+10) + (8-x)]/2

8x = x²+10+8-x

8x= x²-x+18
x²-9x+18 = 0

x' = [-b+√(b²-4.a.c)]/2a       & x" = [-b-√(b²-4.a.c)]/2a

x'= 6  and x" = 3, So we have2 values of x

-2x + 7 = 7

subtract 7 from both sides.

-2x = 0

divide both sides by -2.

x = 0

the value of x is equal to 0.