62 is a system of linear equations problem. You can either graph it, or you can solve it algebraically.
First, let's find the equation for the supertanker. We'll call our variables h, representing hours, and m, representing miles.
m=10h
Since knots are equivalent to nautical miles per hour, we don't need to do any kind of unit conversion.
The cruise ship is slightly trickier. It leaves port two hours after the other, so we'll have to account for that in our second equation.
m=18h-2
The 2 is negative because the cruise ship is behind the other, and our equation should reflect that.
Now we want to find out the number of hours it takes for the distance between the two ships to equal 209. This equation models the situation:
10h+(18h-2)=209
We're adding the two equations together because both of them solve for the same thing: miles, and we need to figure out at which point the distance between the two ships (equivalent to the sum of the distance they have traveled) equals 209.
Now, solving:
10h+(18h-2)=209
28h-2
28h=207
h=7.4
So 7.4 hours.
Your other question is a matter of solving the given equation by plugging a value in for a. We want to find the handicap for a bowler whose average score is 135. That's H=0.8(200-(135)).
After reducing, we get 52. So that's his handicap.
