Tolong yang bisa langsung di jawab, secepatnya

a/18 = 20/15
a/18 = 4/3
a/6 = 4/1
ax1 = 6x4
a = 24

b/16 = 15/20
b/16 = 3/4
b/4 = 3/1
bx1 = 4x3
b = 12

c/10 = 15/20
c/1 = 15/2
2c = 1x15
c = 15/2
c = 7,5