Answer:
x = 5
Step-by-step explanation:
We have: The sum of the measures of angle M and angle R is 90°
M + R = 90°
M = (5x + 10)°
Plug M into (1)
the equation: (5x + 10)° + R = 90° (2)
R=55° into (2)
(5x + 10)° + 55° = 90°
5x + 10 + 55 = 90
5x + 65 = 90
5x = 25
x = 5
To subtract vectors, you simply have to subtract correspondent coordinates.
So, if you have

the subtraction is simply

So, in your case, we have

slope = 13
the slope of the tangent is f'( 4)
given f(x) = x² + 5x , then f'(x) = 2x + 5
and f'(4) = ( 2 × 4 ) + 5 = 13