If i had seven stones and i threw 8 how many stones do i have left? ?

I’m stuck on this i don’t understand.

1. which of the following algebraic equations is equivalent to ? x^n = a a^n = x a^x = n x^a = n 2. 16^1/4= 1/2 2 4 3. (-36)^1/2= -6 1/6 no real number 4. 8^2/3= 4 8 16√2 )^5/2= 7,776 1/7,776 no real number 6. m ^ the square root of a^2m simplified is: 7. the square root of 3^3 times the square root of 2 simplified and in radical form is:

Ab and bc form a right angle at point b. if a= (-3,-1) and b= (4,4) what is the equation of bc?