Answer:
8 ft
Step-by-step explanation:
Use pythagorean theorem. 
. Put 10 and 6 into the equation as b and c.
Therefore, the answer is 8ft.
A diagram is attached. Sorry it's kinda messy.
Answer:
The options are not shown, so i will answer in a general way.
Let's define the variables:
h = number of hats
m = number of mugs.
We know that a total of 1000 items were ordered, then:
h + m = 1000
We also know that we have 3 times more mugs than hats, this can be written as:
m = 3*h
Now we have the system of equations:
h + m = 1000
m = 3*h
To solve these, we usually start by isolating one of the variables in one equation and then replace that in the other equation, but in this case, we already have m isolated in the second equation, then we can replace that in the first equation to get:
h + m = 1000
h + (3*h) = 1000
Now we can solve this equation for h, and find the number of hats ordered.
4*h = 1000
h = 1000/4 = 250
There were 250 hats ordered.
