Question

2 The value of y is directly proportional

to the value of x.
If y = 35 when x = 140, what is the
value of y when x=70

Answer 1

y = 17.5

Explanation:

Given that y is directly proportional to x then the equation relating them is

y = kx ← k is the constant of proportion

To find k use the condition y = 35 when x = 140, then

35 = 140k ( divide both sides by 140 )

0.25 = k

y = 0.25x ← equation of proportion

When x = 70, then

y = 0.25 × 70 = 17.5