Can you me with 15 and 16 and plz show work. ty

According to the general equation of the line which is y= mx +c 
where m is the slope and c is a constant 

we notice here in the general equation that the slope is the coefficient of x when the coefficient of y = 1 

so back to the Q.15 
a) slope = 1/2 
b) slope = 0 
c) slope = 4 
d) we need the equation to be in the general form and the coefficient of y=1, so we devide all the equation by 2 
and it will be as follow y = -5/2 x + 99/2
so the slope = -5/2 

Q.16: 
multiply both sides by 6/5 
x= 7/10