Sergi’s grandmother sent him 10.00 for his birthday. He gave 1/10 of it in church, spent 1/5 of it on a toy , and spent 3/5 of it on a shirt. How much money does he have left ?

1$

Step-by-step explanation:

Start by giving all the fractions a common denominator, here we will use 10.

we already have 1/10

1/5 turns to 2/10

and 3/5 turns to 6/10

add those together and get 9/10

9/10 of 10 is 9$, thats how much he spent

Notice you have 1$ left, that is the answer

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