Ijust need with these math questions

1. Proportions are relatively easy; we can reduce the fractions or check the cross product

4/20 = 1/5 not 1/6

28/36 = 7/9, CHECK

14/18=7/9,  21/27=7/9  CHECK

30/80=3/8, 6/18=1/3, nope

2. Let's check cross products on these

3(40)=120, 5(24)=120, no these are proportions

30(5)=150, 15(10)=150, no, proportions

9(4)=36, 3(14)=42,  CHECK 9/14 is not 3/4

7(24)=14(12) true without multiplying it out; these are proportional

3.

4/16 = m/24

24(4) = 16 m

6(4)(4) = 16 m

m = 6

4.

t/16 = 40/50 = 4/5

5t = 16(4)=64

10t = 128

t = 12.8