You can write every speed as the ratio between the space and time, so in this case you have
1) choice 3
2) commutative property
3) 12x + 8x -3x
common factor of x
x(12+8-3)
or
4x(3+2)-3x
So
if x is the number she spent on each sister and y is the number she spent on each nephew then
180=3x+2y
she wants to spend 15 dollars more on sisters than nephews
so
x=15+y
solve
we have
180=3x+2y and
x=15+y
subsitute 15+y for x
180=3(15+y)+2y
180=45+3y+2y
180=45+5y
minus 45 both sides
135=5y
divide both sides by 5
27=y
solve for x
x=15+y
x=15+27
x=42
she spent $42 on each sister
Find out what the lowest number is that each of the numbers on the bottom of the fractions can divide into evenly.
Slope = Y2-Y1/X2-X1 = 7-(-3)/3-(-2)= 10/5 = 2
