Solve system by elimination -9x - y =-19
5x + y = 15

(1, 10 )

Step-by-step explanation:

Given the 2 equations

- 9x - y = - 19 → (1)

5x + y = 15 → (2)

Adding the 2 equations term by term will eliminate the y- term

- 4x + 0 = - 4

- 4x = - 4 ( divide both sides by - 4 )

x = 1

Substitute x = 1 into either of the 2 equations and solve for y

Substituting into (2)

5(1) + y = 15

5 + y = 15 ( subtract 5 from both sides )

y = 10

solution is (1, 10 )

Therefore the answer is 20.

Step-by-step explanation:

We know that

class interval = range / number of classes

But here number of classes is not given , so we use the formula

class interval = range / ( 1+ 3.322 log N)

where , range =maximum - minimum = 220-100 = 120

N= number of observations = 50

class interval = 120 / ( 1+ 3.322 * log 50) = 18.06

Rounding up to a convinient number

Thus , class intervai = 20

Therefore the answer is 20.