You set (x+15) equal to 40 and solve for x.
x+15=40
-15 -15
x=25
Hope this helps!
9(3+5) is equivalent because factoring a 9 out of both 27 and 45 leaves us with 9(3+5).
The function for the height is

f(0) = 5 cos(0) + 7 = 5 + 7 = 12 (verified)
The period is T = 12 hours.
After 4 hours (t = 4), the height is

A graph of f(t) confirms the answer.
Answer: 4.5 ft
In the 7th and 8th grade combined, there 3+5 girls = 8 girls, and 7+5 boys = 12 boys. If there are only boys and girls, then there are 12+8=20 students in all.
The fraction of girls out of the total is P = 8/20 = 2/5.
Answer:
60 books
Step-by-step explanation:
let the number of books Willy has be x , then
Tammy has 4x books
Willy has 180 fewer books , that is Tammy has 180 more than Willy , so
4x = x + 180 ( subtract x from both sides )
3x = 180 ( divide both sides by 3 )
x = 60
Thus
Willy has 60 books andTammy has 4 × 60 = 240 books
which is 180 more than Willy