Answer:
y = 40
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 = 12 when x = 3 , then
12 = 3k ( divide both sides by 3 )
4 = k
y = 4x ← equation of variation
When x = 10 , then
y = 4 × 10 = 40
