Isolate the <u>v</u><u>a</u><u>r</u><u>i</u><u>a</u><u>b</u><u>l</u><u>e</u> by dividing each side by <u>f</u><u>a</u><u>c</u><u>t</u><u>o</u><u>r</u><u>s</u> that don't contain the <u>v</u><u>a</u><u>r</u><u>i</u><u>a</u><u>b</u><u>l</u><u>e</u>.
We know that the original width was 5, and that after the enlargement the width is 45. To calculate the scale factor we divide the final width between the original one, then: