All the numbers that can go into 40 and 56 are:
1
2
4
8
Hypotenuse^2=12^2+5^2=144+25=169
⇒ hypotenuse =V169=13 cm
8.125 can be written as 65/8. 3.25 can be written as 13/4. 65/8 divided by 13/4 can be written as 65/8 x 4/13. 65 x 4 = 260. 8 x 13 = 104. 260/104 = 65/26 = 2.5