15 you have to do all the steps thank it this I think
So to solve for x, you'll need to combine all the angles and equal it to 720, and from there we can solve.

Combine like terms to get

Subtract 470 on each side to get

Then just divide on each side and you'll get

To find the value of the (x+10) angle, just substitute 125 for x and solve.
Answer:
x = ± 1 , x = ± 
Step-by-step explanation:
Let u = x² , then
- 3x² + 2 = 0 , can be expressed as
u² - 3u + 2 = 0 ← in standard form
(u - 1)(u - 2) = 0 ← in factored form
Equate each factor to zero and solve for u
u - 1 = 0 ⇒ u = 1
u - 2 = 0 ⇒ u = 2
Change the variable u back to x
x² = 1 ( take square root of both sides )
x = ± 1
or
x² = 2 ( take square root of both sides )
x = ± 
Marcus would need to save for 24 weeks in order to purchase a new electronic keyboard.
<h3>Define the meaning of the equation?</h3>
A mathematical assertion in which you use mathematical symbols to demonstrate that two sums are equal.
As per specified data-
- Marcus wishes to save $378 so that he can purchase a new electronic keyboard.
- Every week, he saves $15.75 from his paycheck.
Let 'x' be the number of weeks required to complete the amount.
The equation becomes.
378 = 15.75x
For the number of week required.
x = 378/15.75
x = 24
Thus, Marcus would need to save for 24 weeks in order to purchase a new electronic keyboard.
To know more about the equation, here
brainly.com/question/14107099
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Lets just choose the first one, 3 4 and 5. According to the Pythagorean Theorem,
a^2+b^2=c^2
So lets plug in our numbers.
3^2+4^2=c^2
The answer should be 5, but lets make sure.
3*3 = 9
4*4 = 16
9+16=c^2
25 = c^2
Square root both sides so:
5=c
And sure enough 5 is the last number on that list. The order doesn’t matter as long as the value you are trying to find is the c^2.