Question

the scale of a model railroad set is 3.5 millimeters to one foot if the length of a model car in the set is 150 millimeters what is the length of the car

Answer 1

$\bf \begin{array}{ccll} \stackrel{mm}{model}&\stackrel{ft}{actual}\\ \cline{1-2} 3.5&1\\ 150&x \end{array}\implies \cfrac{3.5}{150}=\cfrac{1}{x}\implies x=\cfrac{150\cdot 1}{3.5}\implies x\approx 42.86$

Answer 2

the answer is 43 ft i just help my little brother with that question and he got it right