It's 60.... i have used the formula
L=r^2mw
and didn't use the value 0.75...
Explanation:
Make a table, listing the x and y coordinates of each square's center of gravity and its mass. Multiply the coordinates by the mass, add the results for each x and y, then divide by the total mass.

The x-coordinate of the center of gravity is 15/14 a.
The y-coordinate of the center of gravity is 47/42 a.
Answer:
false is the answer because it was around in the 1880's
Explanation:
I hope this helped