Question

12. Află numerele necunoscute.
a) (a -80)x 2- 146 = 24
b) (100-b:3)x5 = 490
c) (c:9:3) x 4 = 20​

Answer 1

a) (a-80)×2-146=24

(a-80)×2=24+146

(a-80)×2=170

a-80=170:2

a-80=85

a=85+80

a=165

b) (100-b:3)×5=490

(100-b:3)=490:5

(100-b:3)=98

100-b=98×3

100-b=294

b=294-100

b=194

c) (c:9:3)×4=20

(c:9:3)=20:4

(c:9:3)=5

c:9=5×3

c:9=15

c=15×9

c=135