Explanation:
2 things to remember :
the sum of all angles in a triangle is always 180°.
the inner and the outer angles at a corner point of a triangle are supplementary angles (linear pair) meaning that together they have 180°.
so, the angle F is
F = 180 - 89 - (5x - 7) = 91 - 5x + 7 = 98 - 5x
and then
14x + 1 + 98 - 5x = 180
9x + 99 = 180
9x = 81
x = 9
angle H = 5×9 - 7 = 45 - 7 = 38°