Question

1.Aflati termenii necunoscuti ai proportiilor :
a)5 supra x = 20 supra 7
b)x+1 supra 3 = 10 supra 9

Answer 1

a) x=5*7/20=1,7(5) 
b) x+1=10*3/9=3,3(3)
x=3,3(3)-1=2,3(3)

Answer 2

5/x=20/7
20x=5·7
20x=35
x=35/20 simplificam=7/4=1,75
b)⇒9(x+1)=3·10
9x+1=30
9x=30-1
9x=29
x=29/9=3,(2)