38. express these rates in the lowest terms.

a. $56: 16 kg
b. there are six teachers for every 108 students

39. change to unit rates.

a. $20 for five t-shirts
b. 45 miles in half an hour

38: is A

39: is A

Step-by-step explanation:

1) c 2143.6 cm

2) c 113.0 m

3) a 33.5 ft

4)   d 2 cm

5) c 20 mm

6) 180 in

7) d 120 ft

in problems involving proportions, we can use cross products to test whether two ratios are equal and form a proportion. to find the cross products of a proportion, we multiply the outer terms, called the extremes, and the middle terms, called the means.

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