Paint is mixed 3 parts blue to 1 part white in order to lighten it.   sam needs 12 litres of paint. how much blue and white paint will be needed? he will need ? ?   litres of blue paint. he will need ? ?   litres of white paint.

Sam will need 9 liters of blue paint.

and 3 liters of white paint.

Step-by-step explanation:

Paint is mixed 3 parts blue to 1 part white.

i.e. if 3x liters of blue paint is taken than x liters of white paint is needed.

Sam needs 12 liters of paint.

i.e.   3x+x=12

⇒ 4x=12

Dividing both sides by 4,we get

x=3

Blue paint=3x=3×3=9 liters

White paint=x=3 liters

Hence, Sam will need 9 liters of blue paint.

and 3 liters of white paint.