How can you express (15 + 30) as a multiple of a sum of whole numbers with no common factor?

a)2 × (7.5 + 15)
b)3 × (5 + 10)
c)5 × (3 + 6)
d)15 × (1 + 2)

The area of a rectangle is 10 cm^2. one side of the rectangle is x cm. express the perimeter of the rectangle in terms of x and show that this rectangle cannot have a perimeter of 12 cm. the perimeter of the rectangle in terms of x is __ cm

Solve for x: 5/3 x = 20/21 it's fraction. remember to simplify your fraction

Ineed with question three. i don't understand how i'm supposed to achieve 3 marks.