3.- 5x-6=y
First you leave the variable alone along with 5 and you pass to the other side number 6 with the opposite sign
5x=y+6
then as 5 is multiplying you pass it dividing
y+6 x= 5
4.-2x-3y=8
First you leave the variable with 3 alone and you pass the 2x to the other side subtracting
-3y=8-2x
Then as -3 is multiplying you pass it dividing
y= 8-2x/-3
12.-7x-y=14
First you leave the variable with the 7 alone and you pass the -y to the other side adding
7x=14+y
then as 7 is multiplying you pass it dividing
x=14+y/7
18.-12x-4y=20
First you leave the variable y with the -4 alone and you pass the 12x to the other side subtracting
-4y=20-12x
Then as -4 is multiplying you pass it dividing
y= 20-12x/-4
20.- R-C/N=P
First you leave the R and the C alone and as N is dividing you pass it multiplying
R-C=PxN
Then as C is subtracting you pass it adding
R= (PxN)+C
