Question

If Sally can paint a house in 4 hours, and John can paint the same house in 6 hours, how long will it take both of them to paint the house together?
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I know the answer, but I do not know what is the name of the methods.

EX:
1/n= 1/4 + 1/6
1/n =5/12
n= 12/5

Answer 1

all you have to do is put the math equations into words

Sally's rate = house/4 , or use 1 to represent 1 house
John's ratre = house/6
combined rate = house/4 + house/6
=(5house/12)

time at combined rate = house/(5house/12)
= house(12/5house)
= 12/5

remember we could use the unit 1 for house, since we have 1 house