90 divided by 2= 45 so x=45
2•45=90
So, for the next one y=60 because 90+90=180
3•60-2•45=90
Answer:
see the explanation
Step-by-step explanation:
we know that
The circumference of a circle is equal to

where
D is the diameter
In this problem we have


substitute and solve for D



we know that
The length of the row of quarters is equal to multiply the diameter of the quarter by the number of quarters in the row
so
For 4 quarters in the row, the length is equal to --> 
For 6 quarters in the row, the length is equal to --> 
For 12 quarters in the row, the length is equal to -> 
The GCF of 18 and 39 is 3