You have 13 different books at home that you can read. You want to pick 2 to read and you don't care about what order you read them. How many different combinations can you read 2 books out of 12?

need more info

step-by-step explanation:

his chances of getting a coin of higher value is 4/19

step-by-step explanation:

linear pair postulates

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