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

How tall was Cody on the first day of school last year?

If we let x be Cody's height on the first day of the school last year then, his height on the first day of school this year can be expressed as,

y = x + 0.10x

y is given to be 165. Substituting this to the given equation,

165 = x + 0.10x

Simplifying,

165 = 1.1x

The value of x from the equation is 150 ft.

Answer: 150 ft.