ABC is a triangle
the length of side AB is(x +2)cm
(a)the length of side AC is twice the length of side AB
find an expression for the length AC
AC = 2X + 4 or 2(X + 2)


(b) the length of the remaining side CB is calculated by adding the length of the sides AB and AC together and subtracting 7 cm
CB = x + 2 + 2 x + 4 -7 = 3x-1


(c) the perimeter of ABC is 20 cm
form an equation and slove it to find the length of the side AB
= x + 2 +2x +4 +3x -1 = 20 cm
AB = 6x + 5 = 20 cm
= 20cm -5cm = 15cm ÷ 6cm =2.5cm
x = 2.5 cm
AB = 4.5 cm