Question

ABC is a straight line

The length of AB is four times the length of BC.
AC = 75 cm
Work out the length of AB.

Answer 1

Answer: Length of AB = 60cm

Step-by-step explanation: ABC is a straight line

Let the length of AB and BC be x and y respectively

x = 4y

y = y

∴4y+y =75

5y=75

→y = 15

→x = 4y

∴x = 4×15 = 60cm

∴AB(x) = 60cm

∴BC(y) = 15cm

Answer 2

AB = 60 cm

Explanation:

AC = AB + BC

75 = AB + AB/4

4*75 = 4AB + AB

300 = 5AB

AB = 300/5

AB = 60 cm