Mathematics 36 Online
OpenStudy (anonymous):

the ages of two brothers are in the ratio two to three,but in eight years the ratio of ther ages will be three to four .findtheir presentage

OpenStudy (julie):

hmmmm, so you want to turn this into a series of equations based on the rules outlined in the word problem. and then solve them.

OpenStudy (julie):

so how can you write one of the equations given the first piece of information?

OpenStudy (julie):

e.g. \[y = 2x/3\]

OpenStudy (julie):

where y = younger, and x = older

OpenStudy (julie):

but since there are two variables in this problem, you need a second equation to solve

OpenStudy (julie):

(the two present ages are the two variables)

OpenStudy (julie):

so we know in 8 years, that the ratio will actually be 3/4, not 2/3

OpenStudy (julie):

so: y+8/x+8 = 3/4

OpenStudy (julie):

now that you have two unknown variables (the present ages), and two equations, you can solve the problem by substituting the first (y=2x/3) into the second.

OpenStudy (anonymous):

thank you :)

OpenStudy (julie):

no problem!