It would be 100. If you divide 100/10, you get 10, multiply that by 9 and you’d get 90.
To simply this, you just divide the numerator and denominator by its GCF (Greatest common factor)
Factors of 18 : 1,2,3,6,9,18
Factors of 30 : 1,2,3,5,6,10,15,30
As you can see, the great common factors of 18 and 30 is 6.
So divide 18 by 6 and 30 by 6, and you get 3 and 5
Therefore, the simplest form is 3/5
(10 + 14 + 8 + 16 + 12 + x ) /6 = 13
(60 + x) / 6 = 13
60 + x = 13 * 6
60 + x = 78
x = 78 - 60
x = 18 <=====
Can you show us the triangular prism to help you
