y varies directly with x. When y = 20, x = 50. Find x when y = 36.
Choose one answer.
a. 75
b. 80
c. 90
d. 105

Question

y varies directly with x. When y = 20, x = 50. Find x when y = 36.
Choose one answer.
	 a. 75	
	 b. 80	
	 c. 90	
	 d. 105

anonymous · Answer

what do you get?

saifoo.khan · Answer

90 is your answer.

myininaya · Answer

y=kx
20=k(50)
20/50=k
2/5=k
k=2/5

y=2x/5

36=2x/5
5/2 * 36=x
5*36/2=x
5* 18=x
90=x

anonymous · Answer

correct!

anonymous · Answer

thanks guys! thats what i was thinking!

myininaya · Answer

when you see varies think multiplication
when you see inversely think division

saifoo.khan · Answer

uw.

myininaya · Answer

never forget your constant

anonymous · Answer

you can always forget the constant! when you see "varies directly" just look at how the one is varying, and vary the other the same. Here, y goes from 20 to 36, getting multiplied by 1.8 (36/20). So to vary x, we multiply it by 1.8. 50*1.8 = 90.

myininaya · Answer

no you need the constant to find what the constant is lol