How many solutions does this equation have? -7u = -6u + 8

-7u +6u = 8

-u = 8

u = -8 

A single solution 

-7u = -6u + 8

To determine how many solutions something has, you must always always always solve it first.

Add 6u to both sides.

-7u + 6u = 8

Add like terms.

-u = 8

Divide both sides by -1.

u = -8

So, we now know that there is only one solution.

~Hope I helped!~

Idk idk idk idk idk idk idk idk