Question

решите уравнение 1+3(5x-7)=9+11

Answer 1

1+15x-21=20
15x=-1+21+20 
15x=40 
x=40:15 
x=8/3

Answer 2

1 способ: 
1+3(5х-7)=9+11
3(5х-7)=9+11-1
3(5х-7)=19
5х-7=$frac{19}{3}$
5х=$frac{19}{3}+7$
5х=$frac{19+21}{3}$
5х=$frac{40}{3}$
х=$frac{40}{3}:5$
х=$frac{40}{3}* frac{1}{5}$
х=$frac{8}{3}$
х=$2 frac{2}{3}$

2 способ:
1+3(5х-7)=9+11
1+15х-21=20
15х=20+21-1
15х=40
х=$frac{40}{15}$
х=$frac{8}{3}$
х=$2 frac{2}{3}$