Very simple
[tex]\\ \tt\longrightarrow 5-2y+7y-2-1[/tex]
[tex]\\ \tt\longrightarrow -2y+7y-2-1+5[/tex]
[tex]\\ \tt\longrightarrow 5y-3+5[/tex]
[tex]\\ \tt\longrightarrow 5y+2[/tex]
