Dan’s dog-walking job pays $15 per hour. His job as a car-wash attendant pays $400 each week. Dan wants to know how many hours he needs to spend walking dogs to earn more than $520 in a week. Which three inequalities can model this situation?

we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4

d. you cannot tell because there are no values shown.

to complete this square you have to rotate about the origin 270 degrees clockwise.