serious word problem/math issues

[fancymylotus]

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someone post an age problem and then post the set-up to solve it. i always get mixed up with the wanda is thirty years older than bobby in four years but one fourth of his age now type things.

ALSO...wtf re: sin/cos stuff? i cant do the problems where they give you sin___(fill in degree or radian measure) = ? and then you have to figure out what it equals. anyone know a good way to approach these types of problems?

 

[lifeisgood]

someone post an age problem and then post the set-up to solve it. i always get mixed up with the wanda is thirty years older than bobby in four years but one fourth of his age now type things.

ALSO...wtf re: sin/cos stuff? i cant do the problems where they give you sin___(fill in degree or radian measure) = ? and then you have to figure out what it equals. anyone know a good way to approach these types of problems?

John is 3 years older than the sum of Mary and Bob's ages. Mary is 5 years older than Bob and John is 20 years older than Bob. How old is Mary?

 

[fancymylotus]

John is 3 years older than the sum of Mary and Bob's ages. Mary is 5 years older than Bob and John is 20 years older than Bob. How old is Mary?

now set it up. and answer my other question pleeeeeeeeez😀

 

[lifeisgood]

J = M + B + 3

M = B + 5

J = B + 20

I chose to solve for B b/c I thought it was the easiest to get.

Now substitute...

(B + 20) = M + B + 3

B + 20 = (B + 5) + B + 3

B + 20 = 2B + 8

B = 12

So Mary is 17!!!!

 

[fancymylotus]

J = M + B + 3

M = B + 5

J = B + 20

I chose to solve for B b/c I thought it was the easiest to get.

Now substitute...

(B + 20) = M + B + 3

B + 20 = (B + 5) + B + 3

B + 20 = 2B + 8

B = 12

So Mary is 17!!!!

OH.you set up multiple equations and then substitute.durrrrrrrrh amsie. okie,now what about the ones where its like sin pi/7= and then they give you a bunch of answers. how the f do you figure those out?

 

[dudewhensmydat]

For trig questions like that, reading Math Smart II by Princeton Review was really helpful.