Assuming your solving for y:
py+7=6y+q
-6y -7 -6y -7
(p-6)y = q-7
divide both sides by p-6
y=(q-7)/(p-6)
Percent means parts out of 100
30%=30/100=3/10
'of' means multiply
60 is 30% of what translates to
60=3/10 times what
multiply both sides by 10/3
600/3=what
200=what
the number is 200
This equation has one solution which is -1.5
3x+7=-3x-2
+2. +2
3x+9=-3x
-3x. -3x
9= -6x
/-6. /-6
X= -1.5