You have to make it so they have the same denominator so instead of 4/5 cups of flower he has 8/10 cups of flower then you subtract 1/10 cups of flower and in the end he as 7/10 cups of flower left
The slope of a line can be calculated as follows:

Plug in any two pairs of coordinates from the table, for instance:

This simplifies to 2, therefore, the slope of the line is 2.
The measurement of the given angle is 30 degree.
Here we use trigonometric ratio rule which is sin theta= opposite/hypotenuse
Here theta = 30 degree, opposite =7 and hypotenuse =a
So we get
sin 30 = 7/a
a= 7/sin 30
And value of sin 30 = 0.5
So we get , a = 7/0.5 = 14
So the value of a is 14 .
It has two solutions.
The first solution is x = -7
The second solution is x = 1
Hope this helps!