Question

Find AB
find CD
find AD

Answer 1

see explanation

Explanation:

AC = AB + BC, that is

12 = AB + 5 ( subtract 5 from both sides )

7 = AB

BD = BC + CD, that is

17 = 5 + CD ( subtract 5 from both sides )

12 = CD

AD = AC + CD = 12 + 12 = 24

Hence

AB = 7, CD = 12 and AD = 24

Answer 2

AB = 7, CD = 12, AD = 24

Explanation:

AC = AB + BC → AB = AC - BC

AC = 12, BC = 5

therefore

AB = 12 - 5 = 7

BD = BC + CD → CD = BD - BC

BD = 17, BC = 5

therefore

CD = 17 - 5 = 12

AD = AB + BC + CD

AB = 7, BC = 5, CD = 12

therefore

AD = 7 + 5 + 12 = 24