19x³ + (14x + 4x³)=
You can assume that there is a 1 in front of the parentheses, so you can distribute the one to each term in the parentheses.
19x³ + 1(14x+4x³)=
19x³ + 14x + 4x³=
Then combine like terms to get 23x³ + 14x.
So 19x³ + 14x + 4x³= 23x³ + 14x
10 to the power of 3 is 1000, and 400 divided by 1000 is 0.4 because you move the decimal place over 3 in the number 400 to get 0.4.
The first one is 43/72 which can’t be simplified
The second one is 17/18
Sin is x
tan is y
Hope this helped☺☺
15. 
Add "g" on both sides

Multiply 5 on both sides to get x by itself
x = 5(a + g)
x = 5a + 5g
18. a = 3n + 1
Subtract 1 on both sides
a - 1 = 3n
Divide 3 on both sides to get n by itself
= n
21. M = T - R
Add "R" on both sides to get "T" by itself
M + R = T
24. 5p + 9c = p
Subtract "5p" on both sides
9c = p - 5p
9c = -4p
Divide 9 on both sides to get "c" by itself
c =
or c = 
27. 4y + 3x = 5
Subtract "4y" on both sides
3x = 5 - 4y
Divide 3 on both sides to get "x" by itself
x = 
x = 