Apu has some nickels and some pennies. if the pennies were nickels and the nickels were pennies, he would have 80 cents less than he has now. what is the difference between the number of nickels and the number of pennies he has?

Let X represent the number of pennies.

Let Y represent the number of nickels.

We know that X + 5Y = (Y + 5X) + 80.

4Y = 4X + 80

Y = X + 20

Hence, the difference between the number of pennies and the number of nickels is 20.

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15