Answer:
The ratio is 1:3
Explanation:
Let
x -----> the number of tables in the restaurant
y ----> the number of chairs in the restaurant
we know that
To find out the ratio of tables to chairs in the restaurant, divide the number of tables by the number of chairs
we have

so
The ratio is equal to

Simplify
Divide by 18 both numerator and denominator

therefore
The ratio is 1:3