Answer:
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