Does anyone know the answer. Need help

1yd 1 ft = 1 1/12 1 1/3 1 1/2 1 1/6

Cody was 165cm tall on the first day of school this year, which was 10% taller than he was on the first day of school last year.

Suppose that sahil knows that 45 people with ages of 18 to 29 voted. without using a calculator, he quickly says then 135 people with ages of 30to 49 voted. is he correct? how might sohil have come up with his answer so quickly?