Question

Sabrina used 21 tiles to make a design. She used twice as many blue tiles as red tiles. She used twice as many red tiles as green tiles. How many tiles of each color did Sabrina use?

Answer 1

Sabrina has 21 tiles overall.
Green tiles: x
Red tiles: 2x
Blue tiles: 2 * 2x = 4x

We can write it all as:

21 = x + 2x + 4x
21 = 7x / ÷ 7 (both sides)
x = 3

Doublecheck:

Green tiles: 3
Red tiles: 2 * 3 = 6
Blue tiles: 2 * 6 = 12
All tiles: 3 + 6 + 12 = 21

Correct :)