n 19 -----------> AB/AC=(4/6)=2/3
n 20 ------------> BC/CD=[AC-AB]/[AD-AC]=(6-4)/(9-6)=2/3
n 21-------------> BD/AE=[AD-AB]/[AE]=(9-4)/(12)=5/12
n 22 7 and 28 find the geometric mean of the two number
step 1
Multiply the two numbers together:
28*7=196
step 2
take the square root:
sqrt(196)=14
the answer is 14
n 23 Simplify the ratio 10 ft/30 in---> divided between 2 both members
5 ft/15 in-----> divided between 5 both members ---> 1 ft/3 in
n 24
if AB=4 -------> AB~FG
FG=8
then
AB*factor=FG-------- > 4*factor=8-- > factor=8/4=2
the figure ABCDE is half of the figure FGHJK
then
BC=4
AE=CD=5
and
ED=6
therefore
the perimeter=[4+4+5+5+6]=24 units