HELP!
4. A man can do certain task in 21 hrs, another can do the task in 28 hrs, and a boy can do the task in 48 hrs. Find how long will it take to the task if all work together.

5. A swimming pool can be filled in 6hrs and requires to drain. If the drain was accidentally left open for 6hrs while the pool was being filled, how long did the pool require to fill?

6. Two boys 11 km apart walked toward each other. If their rates are 4km/hr and 5km/hr, when will they be 2km apart?

7. How many ounces of pure silver should be added to 180 ounces, 75% pure, to obtain a mixture of 80% pure?

Question

HELP!
4. A man can do certain task in 21 hrs, another can do the task in 28 hrs, and a boy can do the task in 48 hrs. Find how long will it take to the task if all work together.

5. A swimming pool can be filled in 6hrs and requires to drain. If the drain was accidentally left open for 6hrs while the pool was being filled, how long did the pool require to fill?

6. Two boys 11 km apart walked toward each other. If their rates are 4km/hr and 5km/hr, when will they be 2km apart?

7. How many ounces of pure silver should be added to 180 ounces, 75% pure, to obtain a mixture of 80% pure?

anonymous · Answer

@helder_edwin i need your help again po.. can you help me po?

amistre64 · Answer

find the unit rate, add them up; and take the reciprocal

amistre64 · Answer

5 is missing information

anonymous · Answer

what #?

amistre64 · Answer

youre not spose to post multiple questions at once ... so youll have to figure out what number :)

anonymous · Answer

ahh.. okay po. sorry. :(

amistre64 · Answer

the walking one is simple enough ... takes a little thought, but it practically kindergarten material

amistre64 · Answer

the the ore one is just a system of eqauations

amistre64 · Answer

what are the unit rates for each person in the first one?

anonymous · Answer

ahm , i don't know what to do..

anonymous · Answer

@amistre64 .. do..|dw:1375274971391:dw| right??