Найдите y из пропорций (3y-7) : 5=33:15 64:72=7y+3) : 9 35: (21-5y) = 5:2 53:4=212: (6y-8)

1. (3y-7) / 5 = 33/15

3y-7=33*5/15

3y-7 = 11

3y=11+7

3y=18

y=6

2. 64/72 = (7y+3) / 9

7y+3 = 64*9/72

7y+3 = 8

7y = 5

y=5/7

3. 35 / (21-5y) = 5/2

21-5y = 35*2/5

21-5y=14

-5y=-7

5y=7

y=7/5

4. 53/4 = 212 / (6y-8)

6y-8 = 212*4/53

6y-8 = 1

6y=9

y=9/6

y=1,5