In finding the ratio the given should always have the same units. In the first problem, we convert 10 weeks to days, so 10×7=70 days. The ratio is "40:70", simplifying this, the answer is "4:7"....next problem, we convert 3 weeks to days, so 3×7=21 days. The ratio now is "15:21", simplifying this, the answer would be "5:7".
