1. B si c ajutor va rog

b)
(3*x-11):2+18=20
(3*x-11):2=20-18
(3*x-11):2=2
3*x-11=2*2
3*x-11=4
3*x=4+11
3*x=15
x=15:3
x=5
c)
2*x+4≤10
2*x≤10-4
2*x≤6
x≤6:2
x≤3
x∈N => x∈{0,1,2,3}
[tex] \it a)\ (3\cdot x-11):2 +18 =20|_{-18} \Rightarrow (3\cdot x-11):2 =2|_{\cdot2} \Rightarrow \\ \\ \Rightarrow 3\cdot x-11 =4 |_{+11} \Rightarrow 3\cdot x=15 \Rightarrow x = 5\\ \\ \\\ 2\cdot x+4\leq10|_{-4} \Rightarrow 2\cdot x\leq6 \Rightarrow x\in\{0,\ \ 1,\ \ 2,\ \ 3\} [/tex]