The easiest way to do this is to balance the carbon and hydrogen atoms, and then balance the oxygen atoms.
"C"_10"H"_20"O"_2+"O"_2 rarr "CO"_2 + "H"_2"O"
We have 10 "C" atoms on the LHS, so we must have the same on the right hand side:
"C"_10"H"_20"O"_2+"O"_2 rarr color(red)(10)"CO"_2 + "H"_2"O"
We have 20 "H" atoms on the LHS, so that will give us 10 "H"_2"O" molecules:
"C"_10"H"_20"O"_2+"O"_2 rarr color(red)(10)"CO"_2 + color(blue)(10)"H"_2"O"
On the RHS we have 30 "O" atoms, and on the left, 2. This means we'll need 14 "O"_2 atoms to balance the equation:
"C"_10"H"_20"O"_2+color(green)(14)"O"_2 rarr color(red)(10)"CO"_2 + color(blue)(10)"H"_2"O"