Answer:
a. x=7
b. x=4
c. x=5
d. x=4
e. equation b and d have same solution set.
Step-by-step explanation:
a.
 3x=21
  x=21/3
  x=7.
b.
3x+9-5=16
3x+4=16
3x=12
x=12/3
x=4
c.
6x-9-5=16
6x-14=16
6x=30
x=30/6
x=5
d.
6x+18-10=32
6x+8=32
6x=32-8
6x=24
x=24/6
x=4
e. Equation b and d have the same solution set.
The expression on both sides of the equal in the equation d is are twice of the expression in equation b. So, if (right side)=(left side) is true for some values of x, then 2(right side) = 2(left side) will be true for the same values of x.So we can find the solution without finding the solution set of both the equations.