Question

Afla numerele necunoscute din exercitiile: a) 7+6x(X:4-18)=25
b) 286+(A-113):5=142
c) [93:(X:3)-16x4]x6=186

Answer 1

a) 7+6×(x:4-18) = 25

6×(x:4-18) = 25-7

6×(x:4-18) = 18

x:4-18 = 18:6

x:4-18 = 3

x:4 = 3+18

x:4 = 21

x = 21×4

x = 84

b) 286+(a-113):5=142

286+(a-113)=142×5

286+(a-113)=710

a-113=710-286

a-113=424

a=424+113

a=537

c) [93:(x:3)-16×4]×6=186

93:(x:3)-64=186:6

93:(x:3)-64=31

(x:3)-64=93:31

(x:3)-64=3

x:3=3+64

x:3=67

x=67×3

x=201

Answer 2

$\bf a)\ 7+6\cdot(x:4-18)=25\Big|_{-7} \Rightarrow 6\cdot(x:4-18)=18\Big|_{:6} \Rightarrow x:4-18=3\Big|_{+18} \Rightarrow\\ \\ \\ \Rightarrow x:4=21 \Big|_{\cdot4} \Rightarrow x=84\\ \\ \\ b)\ \ 286+(a-113):5=142 \Big|_{-286} \Rightarrow (a-113):5=-144\Big|_{\cdot5} \Rightarrow \\ \\ \\ \Rightarrow a-113=-720\Big|_{+113} \Rightarrow a=-607$