Red and grey bricks were used to build a decorative wall. The number of red bricks/number of grey bricks was 5/2 There were 140 bricks used in all. How many red bricks were used?

5/2 = 5:2

Lets take 5:2 as 5x and 2x.

5x + 2x = 140

7x = 140

x = 140/7

x = 20

So, 5x = 5x20 = 100 red bricks

and, 2x = 2x20 = 40 grey bricks.

100 + 40 = 140 bricks

So, to build the decorative wall, 100 red bricks and 40 grey bricks were used.