5 is very easy. the transverse cuts at a 90 degree angle, so your equation will look like this
21x+6=90
to find x, you have to work it out using this equation
start by negating the sign and finding out what the sum and equation was before 6 was added.
21x+6=90
-6 -6
21x=84
next, you have to divide both sides by 21 to get the variable (x) to stand alone
(21x)/21=(84)/21
x=4
(use this formula to find number 6!!)
all of the missing angle measurements are 90 degrees. to find this, you have to remember that a straight line is always a 180 degree angle. so, if you have a transversal with only one given angle, you simply subtract 180 from the given angle.
in number 5, it would look like this
180-90=90
these formulas are used for both questions. if you need further help, let me know!