Simplify the expression 3a(3-a)+3(a^2-3)+3a

3 (4 a - 3)

Step-by-step explanation:

Simplify the following:

3 a (3 - a) + 3 (a^2 - 3) + 3 a

3 a (3 - a) = 9 a - 3 a^2:

9 a - 3 a^2 + 3 (a^2 - 3) + 3 a

3 (a^2 - 3) = 3 a^2 - 9:

3 a^2 - 9 - 3 a^2 + 9 a + 3 a

Grouping like terms, 3 a^2 - 3 a^2 + 9 a + 3 a - 9 = (9 a + 3 a) - 9 + (-3 a^2 + 3 a^2):

(9 a + 3 a) - 9 + (-3 a^2 + 3 a^2)

9 a + 3 a = 12 a:

12 a - 9 + (-3 a^2 + 3 a^2)

3 a^2 - 3 a^2 = 0:

12 a - 9

Factor 3 out of 12 a - 9:

 3 (4 a - 3)

35-60 students are taking math.

14 ft 7 inches

step-by-step explanation:

since each model inch corresponds to 25 real inches, 7 model inches will correspond to

7×25" = 175"

at 12" per foot, that is 14 feet, 7 inches.