Answer:
see explanation
Step-by-step explanation:
Given that y varies inversely as x then the equation relating them is
y = [tex]\frac{k}{x}[/tex] ← k is the constant of variation
To find k use the condition y = 5 , x = 21
k = yx = 5 × 21 = 105
y = [tex]\frac{105}{x}[/tex] ← equation of variation
When x = 10, then
y = [tex]\frac{105}{10}[/tex] = 10.5
