Question

Vă rog , e foarte urgent ! Dau 16 puncte !!
1. 15:[11-(7•5-9•9:a:3):8+2•4]•3=3

2. {[(2•a+3)•4]-5}:9=15

Answer 1

1)
3:3=1
15:[11-(7x5-9:a:3):8+2x4]=1
[....]=15x1=15
11-(...):8+8=15
11-(...):8=7
(...):8=4
(...)=32
35-81:3:a=32
35-27:a=32
27:a=3
a=9
2)
{[(2xa+3)x4]-5}:9=15
{...}=15x9=135
[...]=135-5=130
(...)=130:4=32,5
2xa=29,5
a=14,75