Multiply the bracket(s) to get rid of the brackets as this in the first step in BIDMAS/BODMAS.

#color(orange)(-7.3 xx x=-7.3x#

#color(blue)(-7.3 xx 7.1=-51.83#

This gives us #color(blue)(-100.47)=color(orange)(-7.3x)color(blue)(-51.83)color(orange)(-7.9x)#

Collect like terms on each side if possible, in this instance only the right...

#color(orange)(-7.3x + -7.9x=-15.2x#

This therefore leaves us with:

=> #color(blue)(-100.47)=color(orange)(-15.2x)color(blue)(-51.83)#

We want #x# on its own so therefore we do the opposite of #color(blue)(-51.83# which is adding #color(blue)(51.83# to both sides, as you have to add to both sides of the equation...

#color(blue)(-100.47)=color(orange)(-15.2x)color(blue)(-51.83)#

=> #color(blue)(-48.64)=color(orange)(-15.2x) color(Blue)((+51.83)#

Therefore to solve for #x#, we divide the total over how many #x's# we have which goes to...

#color(red)(x=-48.64/15.2#

As #-1 xx -1=1#

#color(red)(x=48.64/15.2=3.2#

Round if necessary, But in this case it's not, so leave it as:

=> #color(red)(x=3.2)#