15 points : )
find the value of x.

Question 4: -11

Question 5: -7

Step-by-step explanation:

Four

Every triangle has 180 degrees.

So all three angles add to 180

Equation

60 + 80 + x + 51 = 180

Solution

Combine the like terms on the left. This is the first time I've seen x be a negative value. Almost all of the time it isn't, which should make you wonder.

191 + x = 180    

Subtract 191 from both sides.

191 - 191 + x = 180 - 191

x = - 11

Five

If a triangle is a right triangle and one of the angles is 45, then so is the other one.

Proof

a + 45 + 90 = 180         Combine like terms on the left

a + 135 = 180                Subtract 135 on both sides.

a + 135-135=180-135    Combine the like terms

a = 45

Statement

That means 52 + x = 45 and here is another negative answer. Subtract 52 from both sides

52 - 52 + x = 45 - 52    Combine like terms.

x  = - 7

answer

step-by-step explanation: