Tom bought a pizza. he ate 1/3 of the pizza and gave some of it to his brother. he was then left with 1/5 of the pizza. what fraction of the pizza did tom give his brother?

7/15

Step-by-step explanation:

first recognise that 3/3 is a whole pizza and so is 5/5.

Secondly make all the numbers to have the same denominator

So times both denominators of the fractions together; 5x3=15

Now find 1/3 of 15. Do this by dividing 15 by 3. This equals 5.

So 1/3 is equal to 5/15

Now do the same for 1/5. 15 divided by 5, this equals 3.

So 1/5 is equal to 3/15

Now that we know that the whole pizza is 15/15

We minus 1/3 from 15.

15-5=10.  So we now have 10/15 left.

now we know that 'x' is representative of the amount of pizza Tom gave to his bother.

10/15 - 3/15 = x

x = 7/15

So out of the whole pizza (15/15), tom ate 5/15 and was left with 3/15 meaning he gave 7/15 to his brother.

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