8 because when you flip one coin there is 2 outcomes: heads and tails. Therefore if you flip 3 of them it is 2*2*2=8
A rate is a ratio of two quantities: miles per hour, calories per cookie,dollars per person, ... a unit rate just specifies the units (miles, hours) of<span> the two quantities.</span>
To get the points at which the two boats meet we need to find the equations that model their movement:
Boat A:
vertex form of the equation is given by:
f(x)=a(x-h)^2+k
where:
(h,k) is the vertex, thus plugging our values we shall have:
f(x)=a(x-0)^2+5
f(x)=ax^2+5
when x=-10, y=0 thus
0=100a+5
a=-1/20
thus the equation is:
f(x)=-1/20x^2+5
Boat B
slope=(4-0)/(10+10)=4/20=1/5
thus the equation is:
1/5(x-10)=y-4
y=1/5x+2
thus the points where they met will be at:
1/5x+2=-1/20x^2+5
solving for x we get:
x=-10 or x=6
when x=-10, y=0
when x=6, y=3.2
Answer is (6,3.2)
, where 
.