Answer:
Sean is not correct. The answers are 100°, 35° and 45°.
Step-by-step explanation:
In my working, I labeled the part without a variable as a°.
Step 1: a° + 80° = 180° ( angles on a straight line sum up to 180° )
Step 2: a° = 180° - 80°. This is because 80 moves from the left side of the equation to the right side of the equation which affects it's sign( from + to -)
Step 3: a° = 100° . Subtract 80 from 180.
So we know that 100 is correct. Let's find the remaining angles.
Step 4: a° + ( x - 5 )° + ( x + 5 )° = 180° ( angles in a triangle sum up to 180°)
Step 5: 100° + x - 5° + x + 5° = 180°. Fix in the values of each variable correctly. Here we only know the value of variable a.
Step 6: (100° - 5° + 5°) + (x + x) = 180°. Group like terms to make calculations easier.
Step 7: 100° + 2x = 180°. -5+5 is the same as 5-5 which would give you 0. 0 + 100° is 100°.
Step 8: 2x = 180° - 100°. Move like terms to one side.
Step 9: 2x= 80°. Subtract 100° from 180° to get 80°
Step 10: 2x/2 = 80°/ 2. Divide both sides by 2.
Step 11: x= 40°. But this isn't the final answer. This is just the answer for all the x you see in the diagram. So fix in the values correctly.
Step 12: ( x-5° ). State it for your teacher to know which question you are given an answer to. From our calculations, we know that x = 40°.
Step 13: (40° - 5°)
Step 14: ( 35°). 40 minus 5 is 35.
Step 15: 35°. multiply the figure in the bracket by one. We can't leave our answer in the bracket.
Step 16: (x + 5). Using the same knowledge, fix in the values and do as the operation sign says.
Step 17: ( 40° + 5 °)
Step 18: (45°)
Step 19: 45 °
Step 20: Sean is not right because the angles in the triangle are 100°, 35° and 40°.
