A jar is full of 100 coins. All of the coins are either nickels or dimes. a. The value of the coins is $6.35. Write a linear system representing this equation.
b. Solve the system to determine how many of each type of coin is in the jar.

73 nickels, 27 dimes

Step-by-step explanation:

x+y=100

5x+10y=635

x=100-y

5(100-y)+10y=635

500-5y+10y=635

500+5y=635

5y=135

y=27

5x+10(27)=635

5x+270=635

5x=365

73

73+27=100

take it another

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