Answer:
y = 130
Explanation:
given that y varies directly with x and z then the equation relating them is
y = kxz ← k is the constant of variation
to find k use the condition y = 150 when x = 2.5 and z = 12 , then
150 = k × 2.5 × 12 = 30k ( divide both sides by 30 )
5 = k
y = 5xz ← equation of variation
when x = 4 and z = 6.5 , then
y = 5 × 4 × 6.5 = 20 × 6.5 = 130