18 × (- 19) of 9 and 19 We should simplify the calculation

18 × (- 19) of 9 and 19 We should simplify the calculation

=（9*19+18）/19*(-19)=-(9*19+18)=-189

18 / 9 and 19 * (- 6)

The original formula = (9 * 19 + 18) / 19 * (- 6) = - 189 * 6 / 19 = 1134 / 19 = - 59 and 13 / 19

How much is √ 18 - √ 9 / 2?

√18-√9/2=3√2-3/2

Answer the following questions according to the ratio of 18:6 = 9:3
1. If the first item is 18-6, how should the second item be changed to make the proportion still valid? If the third item is 9 times 2, how should the fourth item be changed to make the proportion still valid?
2. If the third and fourth items are divided by 3, is the proportion valid? Why? If the first and third items are multiplied by 3, and the fourth item is divided by 3, how can the second item be changed to make the proportion still valid?

1. If the first item 18-6, the second item 6 should subtract 2 to make the proportion still hold
If the third item is 9 times 2, the fourth item must be multiplied by 2 to make the proportion still hold
2. If both the third and fourth items are divided by 3, the ratio still holds, because the ratio on the right side remains unchanged
If the first and third terms are multiplied by 3, and the fourth term is divided by 3, the second term must be divided by 3 to make the proportion still hold