Finding solution of differential equation using euler numerical method $\frac{dy}{dx}=0.3y-10$ and $0\le x\le 3$ and $x=0,y=40.$

What i have tried

${y}_{n}={y}_{n-1}+h\cdot f({x}_{n-1},{y}_{n-1})$

Where $f(x,y)=0.3y-10.$

I have a doubt that what should i take width interval $h$ in above question.(which is not mention here)

Can anyone please explain me what i take value of $h$. Thanks

What i have tried

${y}_{n}={y}_{n-1}+h\cdot f({x}_{n-1},{y}_{n-1})$

Where $f(x,y)=0.3y-10.$

I have a doubt that what should i take width interval $h$ in above question.(which is not mention here)

Can anyone please explain me what i take value of $h$. Thanks