There are 12 red and blue pencils on a desk. Twice as many red as blue.

How many red pencils on the desk?

There are 12 pencils.

Red pencils + Blue pencils = 12

There are twice as many red pencils as blue pencils

Red pencils = Blue x 2

Substitute Red Pencils in the first question with blue x 2

So the first equation is 2 x blue + blue = 12

This will equal 3 blues = 12

Divide both sides by 3

Blues = 4 pencils

Reds = 2 x blues

Reds = 2 x 4

Red = 8 pencils