To find the ratio of x:z, we will make the value of y common in both ratios by finding the Least Common Multiple (LCM). Calculations: LCM of the y -values (5 and 16) is 80 . First ratio: x:y=12:5 To make the y -value 80 , multiply both terms by 16 (since 80∕5=16 ). ‌x:y=(12×16):(5×16) ‌⇒x:y=192:80 Second ratio: z:y=21:16 To make the y -value 80 , multiply both terms by 5 (since 80∕16=5 ). ‌z:y=(21×5):(16×5) ‌⇒z:y=105:80 Now, we can find the ratio of x:z from the adjusted ratios: ⇒x:z=192:105 To simplify, divide both terms by their Greatest Common Divisor (GCD), which is 3 . ‌⇒x:z=(192∕3):(105∕3) ‌⇒x:z=64:35