Question

if y directly proportional to x and if y =5 when X= 2, find the value of y when x= 7

Answer 1

Hai friend ,

here is your answer,

y∝ x

so,

y=kx
y/x =k

here k is the proportionality constant

First case ➡

x =2
y =5


so here k=5/2

Applying k to second case

Second case ➡

y=?
x=7

k=y/x


5/2 = y/7

5/2*7=y

35/2=y

17.5=y


Hope helped!!

Answer 2

given 
y∞x
y/x = k( constant)
5/2 =k
i)if x= 7 , y= ?
y/x = k
y/7 =5/2
⇒y = (5*7)/2
∴y = 35/2
y= 17.5