ryan has $250 he spent 40% of his money on a skateboard and 20% on a helmet. what percentage of his money did he spend

Mathematics

2 answers:

Mamont248 [21]2 years ago

7 0

He spent 60% of his money

lisov135 [29]2 years ago

7 0

He spent 60% of his moner

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What is the determinant of the coefficient matrix of this system? <br> 4x-3y=-8 <br> 8x-3y=12

gladu [14]

The coefficient matrix is build with its rows representing each equation, and its columns representing each variable.

So, you may write the matrix as

$\left[\begin{array}{cc}\text{x-coefficient, 1st equation}&\text{y-coefficient, 1st equation}\\\text{x-coefficient, 2nd equation}&\text{y-coefficient, 2nd equation} \end{array}\right]$

which means

$\left[\begin{array}{cc}4&-3\\8&-3\end{array}\right]$

The determinant is computed subtracting diagonals:

$\left | \left[ \begin{array}{cc}a&b\\c&d\end{array}\right]\right | = ad-bc$

So, we have

$\left | \left[\begin{array}{cc}4&-3\\8&-3\end{array}\right] \right | = 4(-3) - 8(-3) = -4(-3) = 12$

8 0

2 years ago

Which expressions are equivalent to 10a - 25 + 5b

sergey [27]

Answer:

Step-by-step explanation:

$10a-25+5b\\\\-2(-5a-25+5b)=(-2)(-5a)+(-2)(-25)+(-2)(5b)\\=10a+50-10b\qquad NOT\\\\(2a-5+b)(5)=(2a)(5)+(-5)(5)+(b)(5)=10a-25+5b\qquad YES\\\\10(a-2.5+0.5b)=(10)(a)+(10)(-2.5)+(10)(0.5b)\\=10a-25+5b\qquad YES\\\\(-2a+5-b)(-5)=(-2a)(-5)+(5)(-5)+(-b)(-5)\\=10a-25+5b\qquad YES\\\\-10(-a-2.5-0.5b)=(-10)(-a)+(-10)(-2.5)+(-10)(-0.5b)\\=10a+25+5b\qquad NOT$