Question

(5x-39).7+3=80

Answer 1

\((5x-39)\cdot7+3=80\\\Rightarrow (5x-39)\cdot7=80-3\\\Rightarrow (5x-39)\cdot7=77\\\Rightarrow 5x-39=77:7\\\Rightarrow 5x-39=11\\\Rightarrow5x=11+39\\\Rightarrow5x=50\\\Rightarrow x=50:5=10\\Vậy:x=10\)

Answer 2

(5x - 39).7 + 3 = 80

(5x - 39).7 = 80 - 3

(5x - 39).7 = 77

5x - 39 = 77 : 7

5x - 39 = 11

5x = 11 + 39

5x = 50

x = 50 : 5

x = 10

Answer 3

$(5x-39).7+3=80$

$\Rightarrow (5x-39).7=77$

$\Rightarrow 5x-39=11$

$\Rightarrow 5x=50$

$\Rightarrow x=10$

Vậy$\mathrm{x\; =}10$