How do you add and subtract negative numbers?

When you add two positive numbers, the answer is always positive. (Ex. 5 + 5 = 10)

When you add two negative numbers, the answer is always negative. (Ex. -5 + -5 = -10)

When you add a positive and negative number, subtract, and keep the sign of the greater number. (Ex1. -45 + 7 = -38. Subtract 45 - 7, and keep the negative sign of -45 becuase it is greater.) (Ex2. 67 + -5 = 62)

When you subtract two positive numbers, if the second number is less than the first, the answer is positive. (Ex1. 10 - 6 = 4) If the second number is greater than the first, the answer is negative. (Ex2. 10 - 17 = -7)

When you subtract two negative numbers, if the second number is less than the first, the answer is negative. (Ex1. -9 - -4 = -5) If the second number is greater than the first, the answer is positive. (Ex2 -9 - -21 = 12)

When you subtract a positive number and a negative number, add, and keep the sign of the lesser number. (Ex1. -12 - 56 = -68. Add 12 + 56, and keep the negative sign of -12 because it is less.) (Ex2. 67 - -89 = 156)

Also, when you add the same number with different signs, the answer is always zero.

(Ex. -1 + 1 = 0)

( -2 + 2 = 0)

( 3 + -3 = 0)

( -4 + 4 = 0) etc..

56.6

step-by-step explanation:

the ratio of the perimeters is equal to the scale.

the ratio of the areas is equal to the square of the scale.

34 / 20 = k

a / 19.6 = k²

substituting:

a / 19.6 = (34 / 20)²

a = 19.6 (34 / 20)²

a ≈ 56.6