Answer:
15 miles
Step-by-step explanation:
Let's say the dock is at the origin on a coordinate plane and each unit is 1 mile. If the boat travels 9 mile due north, that means that we move up from the origin (0, 0) 9 units to point A (0, 9). Now, this boat moves 12 miles due west, so we will go 12 units to the left of (0, 9) to point B (-12, 9). See the attached drawing (sorry for the crudeness).
Notice that this is a right triangle with legs of 9 and 12. That means the distance from the boat to the dock is just the hypotenuse, so use the Pythagorean Theorem: distance = 
Thus, the answer is 15 miles.
Hope this helps!
The most simplified version would be:
Question 4- You need to subtract the shortest bolt from the longest bolt, or 1 1/4 minus 3/8. Make 1 1/4 improper and make the denominator 8 so multiply 5x2=10 and 4x2=8. 10/8 - 3/8 equals 7/8 and thats your final answer. Hope this helped ;)
Triangle ABE is isosceles / Given
AB congruent to AE / Def isosceles
angle ABE congruent to angle AEB / Property of isosceles triangles
angle ABD congruent to angle AEC / Subst different name for same angles
BD congruent to EC / Given
triange ABD congruent to triange AEC / Side Angle Side
Always remember that percent means "out of 100". That means the 40%=40/100=.4
so 40% of 120 is equivalent to .4(120)=48
Hope I helped
