tolong ya...... nmr 2 dan 3

2)
a.
x/4 = 9/12
x = (9)(4) / 12
x = 36/12
x = 3

b)
9/x = 15/12
x = (9)(12) / 15
x = 108/15
x = 7,2

c)
15 / (y+4) = 20/16
20 ( y +4) = 15 (16)
20y + 80 = 240
20y = 160
y= 160/20
y = 8

2.
a)
3x = 21
x= 21/3
x = 7

b)
4x - 1 = 29
4x = 30
x = 30/4
x =  7,5

c)
6 (x+3) =  12
6x + 18 = 12
6x = -6
x = -1