Answer:
y = 60
Step-by-step explanation:
Given that y varies directly with x then the equation relating them is
y = kx ← k is the constant of variation
To find k use the condition y = 20 when x = 10, then
20 = 10k ( divide both sides by 10 )
2 = k
y = 2x ← equation of variation
When x = 30, then
y = 2 × 30 = 60
