math
posted by Anonymous on .
I need help solve the equation by fractions
8/(21y) = 12/(y+19)
I think the answer is y = 5, i just need to know how to do work out. i done some solution like this
first multiply by(21y)(y+19)(assuming that y = 21 and y = 19:
(21y)(y+19)8/(21y) = (21y)(y+19)12/(y+19)
then cancel and multiply out the brackets:
8(y+19) = 12(21y)
that is
8x+152 = 12x96
finally,rearrange the equation as
160x = 104

y=5 is correct.
To multiply by (21y)(y+19), y must not equal 21 nor 19.
Correct until
8(y+19) = 12(21y)
Expand:
8y+152=12y+252
20y=100
y=5