Question

Ephrahim has 12 coins in his pocket, consisting of quarters and dimes only. If he has $2.10 in his pocket, how many of each coin does he have?

Answer 1

X = quarters ($ 0,25)
y = dimes ($ 0,10)

     x  +     y = 12
0,25x+0,1y =  2,1

eliminasi y:
0,1x + 0,1y = 1,2
0,25x+0,1y = 2,1 (-)
        -0,15x = -0,9
                x = 6 coins

subtitusi x = 6:
y = 12 - x
   = 12-6
   = 6 coins

he has each 6 coins

Answer 2

Quarter = x
dimes = y

1 quarter = 25 cent = $0,25
1 dimes = 10 cent = $0,1

x + y = 12...........x = 12 - y
0,25x + 0,1y = 2,10

0,25x + 0,1y = 2.10
0,25(12 - y) + 0,1y = 2,10
3 - 0,25y + 0,1y = 2,10
-0,15y =-0.9
y = 6

x =12 - 6 = 6

Eprahim has 6 quarters ($1,50) and 6 dimes ($0,6)