Multiply both numerators and denominators. Result fraction keep to lowest possible denominator GCD(3, 2) = 1. In the following intermediate step, it cannot further simplify the fraction result by canceling.
In other words - one half multiplied by three = three halfs.
(I believe you have a typo in your answer where the scale is 1:110. Hard to believe one would make a model house 110 times the size of a physical house, haha!)
