Answer: There are 64 red bricks to made a walkway.
Step-by-step explanation:
Since we have given that
Total number of bricks = 80
Let the number of grey bricks be x
Let the number of red bricks be 4x
According to question,
[tex]x+4x=80\\\\5x=80\\\\x=\frac{80}{5}\\\\x=16[/tex]
So, red bricks is given by
[tex]4\times x=4\times 16=64[/tex]
So, there are 64 red bricks to made a walkway.