Answer:
5) x=19 ft.
6) x=3 cm.
7) x=50 ft.
8) 56 mm.
Step-by-step explanation:
All of these problems require proportions. For example, in #5, the smaller rectangle has a width of 8 ft. and a length of 24 in. and the larger rectangle has a length of 57 in. but the width is not given. Now, we know that

. Cross-multiply to get 456=24x. Divide 24 on both sides to get x=19 ft.