(-4,15),(-7,10)
slope = (10 - 15) / (-7 - (-4) = -5 / (-7 + 4) = -5 / -3 = 5/3
there can be 2 answers to this...depending on the point u use...
y - y1 = m(x - x1)
slope(m) = 5/3
using point (-4,15)...x1 = -4 and y1 = 15
now we sub
y - 15 = 5/3(x - (-4)..not done yet
y - 15 = 5/3(x + 4) <=== this is one answer
y - y1 = m(x - x1)
slope(m) = 5/3
using point (-7,10)....x1 = -7 and y1 = 10
now we sub
y - 10 = 5/3(x - (-7)...not done yet
y - 10 = 5/3(x + 7) <=== and here is the other answer
So for this, we will be using dimensional analysis:

In short, he should receive ¥8835.30.
Make a graph and start at the origin (0,0) count down 5 units and across to the right 4 units. Put a dot here. For every 1 unit the line moves to the right, it moves down 3.
3.5x-10>-3 add 10 to both sides
3.5x>7 divide both sides by 3.5
x>2
... now for the other inequality:
8x-9<39 add 9 to both sides
8x<48 divide both sides by 3
x<6
So we have x>2 and x<6, so the compound inequality is:
2<x<6 and this means that the solution set is:
x=(2, 6)
When (2x-20)+86=0
2x-20=-86
2x=-46
x=-23