Answer: He has to save at least $420 .
Step-by-step explanation:
Hi, to answer this question we have to write an inequality using the information given:
The amount he has already saved (75) plus the money he still needs to save (x) must be higher or equal to the cost of the Smartphone and accessories.
75 +x ≥ 495
Solving for x:
x ≥ 495-75
x ≥ 420
He has to save at least $420.
Answer:
12 2/5 hours
Step-by-step explanation:

12 2/5 hours have been logged in all.
Answer: 
<u>Step-by-step explanation:</u>
![\ \ \dfrac{3}{4}-x\bigg(\dfrac{1}{2}-\dfrac{5}{8}\bigg)+\bigg(-\dfrac{3}{8}x\bigg)\\\\\\=\dfrac{3}{4}\bigg(\dfrac{2}{2}\bigg)-x\bigg[\dfrac{1}{2}\bigg(\dfrac{4}{4}\bigg)-\dfrac{5}{8}\bigg]+\bigg(-\dfrac{3}{8}x\bigg)\\\\\\=\dfrac{6}{8}-x\bigg(\dfrac{4}{8}-\dfrac{5}{8}\bigg)-\dfrac{3}{8}x\\\\\\=\dfrac{6}{8}-x\bigg(-\dfrac{1}{8}\bigg)-\dfrac{3}{8}x\\\\\\=\dfrac{6}{8}+\dfrac{1}{8}x-\dfrac{3}{8}x\\\\\\=\dfrac{6}{8}-\dfrac{2}{8}x\\\\\\=\dfrac{3}{4}-\dfrac{1}{4}x\quad \text{(reduced both fractions)}](https://tex.z-dn.net/?f=%5C%20%5C%20%5Cdfrac%7B3%7D%7B4%7D-x%5Cbigg%28%5Cdfrac%7B1%7D%7B2%7D-%5Cdfrac%7B5%7D%7B8%7D%5Cbigg%29%2B%5Cbigg%28-%5Cdfrac%7B3%7D%7B8%7Dx%5Cbigg%29%5C%5C%5C%5C%5C%5C%3D%5Cdfrac%7B3%7D%7B4%7D%5Cbigg%28%5Cdfrac%7B2%7D%7B2%7D%5Cbigg%29-x%5Cbigg%5B%5Cdfrac%7B1%7D%7B2%7D%5Cbigg%28%5Cdfrac%7B4%7D%7B4%7D%5Cbigg%29-%5Cdfrac%7B5%7D%7B8%7D%5Cbigg%5D%2B%5Cbigg%28-%5Cdfrac%7B3%7D%7B8%7Dx%5Cbigg%29%5C%5C%5C%5C%5C%5C%3D%5Cdfrac%7B6%7D%7B8%7D-x%5Cbigg%28%5Cdfrac%7B4%7D%7B8%7D-%5Cdfrac%7B5%7D%7B8%7D%5Cbigg%29-%5Cdfrac%7B3%7D%7B8%7Dx%5C%5C%5C%5C%5C%5C%3D%5Cdfrac%7B6%7D%7B8%7D-x%5Cbigg%28-%5Cdfrac%7B1%7D%7B8%7D%5Cbigg%29-%5Cdfrac%7B3%7D%7B8%7Dx%5C%5C%5C%5C%5C%5C%3D%5Cdfrac%7B6%7D%7B8%7D%2B%5Cdfrac%7B1%7D%7B8%7Dx-%5Cdfrac%7B3%7D%7B8%7Dx%5C%5C%5C%5C%5C%5C%3D%5Cdfrac%7B6%7D%7B8%7D-%5Cdfrac%7B2%7D%7B8%7Dx%5C%5C%5C%5C%5C%5C%3D%5Cdfrac%7B3%7D%7B4%7D-%5Cdfrac%7B1%7D%7B4%7Dx%5Cquad%20%5Ctext%7B%28reduced%20both%20fractions%29%7D)
Step-by-step explanation:
To prove :
( 1 - sin x ) ( 1 + sin x ) = sec² x
LHS : -
( 1 - sin x ) ( 1 + sin x )
Formula / Identity : -
( a - b ) ( a + b ) = a² - b²
Here,
a = 1
b = sin x
( 1 - sin x ) ( 1 + sin x )
= 1 - sin² x
Identify : -
sin² θ + cos² θ = 1
cos² θ = 1 - sin² θ
Similarly,
1 - sin² x
= cos² x
= RHS
Hence verified.