Say you have a box and theres one fifteen on two sides and one five on the other two side 15+15=30 and 5+5=10 and 30+10=40 and 40x2=80
Answer:$80
Gradient of the line formed;
m=

m=

m=

y=mx+c
y=

Replacing for x and y;
1=-3/11*(-5)+c
1=15/11+c
c=1-15/11
c=-4/11
y=
Plug in x.
3+y=8
Subtract 3 on both sides. (do the inverse of addition; which is subtraction)
y=5
Check your answer.
3+5=8
8=8
That checks out! y is definitely 5.
I hope this helps!
~kaikers
100%=9.99
×%=6.75
9.99x=100×6.75
9.99X=675
X=675/9.99
67.567% or 67.57
you could also say:
6.75/9.99=0.67567
0.67567×100=67.57%
so the markup is 100%-67.57%=32.43%
32.43%off