Algebra 3 word problems!! Need desperate help!! Part 3!!?

Question

FOR PROBLEMS 11 AND 12: A military helicopter travled at 140 mph. A motorcycle travled at 60 mph. The motorcycle travled three hours longer than the helicopter and went 100 miles farther than the helicopter.

11. How far did the motorcycle travel?
12. How many hours did the helicopter fly?

13. A bakery wants to make desert out of chocolate and almonds. if the cost of chocolate is $.75 a pound and the cost of almonds is $.50 a pound, then how many pounds of each should be used to make 30 pounds of the dessert that costs the bakery $.65 a pound?

14.If a dairyman has 475 pounds of milk having a content of 2.5% butterfat, how many pounds of skimmed milk (with no butterfat) must he remove to have milk with a content of 4% butterfat?

15. A pharmacist must reduce a 50-ounce quantity of a 12% solution of a particular medicine to an 8% solution by adding pure water. How much water does he have to add?

Answer 1

I'll answer 11 and 12.

We know that the speed is given by (distance/time).

So let the distance travelled be x and the time be y,

So for the heli the equation is

x/y = 140 or x-140y=0------1)

And for the motorcycle it is

x+100/y+3=60 or x-60y=80--------2)

Solving 1) and 2) we have

x=140 and y=1

So that is the distance travelled by heli is 140 and time is 1 hr.

But the motorcycle travels 100 miles longer. So x+100=240 miles
Thats one answer.

For 12 we have y=1. But the motorcyle travelled 3 hrs longer so 1+3=4hours

So Answers

11) 240miles
12) 4 hours.

You've got to think and I'm sure you'll get it. 13,14,15 are easy.

Best of luck.