I am struggling to complete this problem. I went to class but I didn't quite pay that much attention how to do this particular kind of problem... can someone help please.

Question

kc_kennylau · Answer

can you just say the problem lol

221emily · Answer

Suppose y varies directly with x, and y=25 when x=140. What is the value of x when y=36?

a.) 140
b.) 165
c.) 201.6
d.)176

I know that you are supposed to use y/x but I just can't remember

kc_kennylau · Answer

the ratio is y:x=25:140

hartnn · Answer

yes
when y varies directly with x, y/x = k = constant

kc_kennylau · Answer

so when y increases to 36, it's actually (36/25) times 25.
therefore x becomes (36/25) times 140.

hartnn · Answer

so when y=25 , x= 140
first find the value of k, can you ?

221emily · Answer

0.178571428 I think

hartnn · Answer

the value for k ? 
you can keep k as 25/140 too 
so,
when y = 36 
y/x = k
36/x = 25/140
can you find x from here ?

221emily · Answer

151 ?

hartnn · Answer

no...how you got 151 ?
 36/x = 25/140
36 = 25x/140
36*140 = 25 x
x= 36*140/25 =...?

221emily · Answer

201.6

221emily · Answer

I think I got it thank you :)

hartnn · Answer

yes correct :)
welcome ^_^