Question

when my brother was 10, I was half of my brother age, now my brother 30,how old am I? ​

Answer 1

Given : When your Brother Age is 10, You were half of his Age

$\mathrm{:\implies Your\;Age\;when\;your\;Bro's\;Age\;is\;10 = \dfrac{10}{2}}$

$\mathrm{:\implies Your\;Age\;when\;your\;Bro's\;Age\;is\;10 = 5}$

Now : Your Brother's Age is 30

It tells us : 20 years have passed since he was 10 years old

$\mathrm{:\implies Age\;of\;You,\;after\;20\;years = 5 + 20}$

$\mathrm{:\implies Age\;of\;You,\;after\;20\;years = 25}$

$:\implies \texttt{You are 25 Years Old when your Brother is 30}$