Respuesta :

melb156
X will be the amount of 1 dollar bill and y the 5 dollar bill

x1 + y5 = 40
x + y = 12

(I'm going to solve for x first, so multiply the bottom equation by negative 5)

x1 + y5=40
x-5+y-5= -60

(cross out the y and solve)

x-4 = -20

(divide)

x= 5

(place it in the equation you didn't use)

5 + y = 12

y = 7
he has 7 fives and 5 ones

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