What is the value of $b$ for the following equation: $5 a - 4 b = 2$ and $a + b = 4$ ?
(Use cross multiplication method)

b = 1

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b = 2

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b = 3

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b = 4

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Solution

The correct option is A $b = 2$
Using formula for cross multiplication method:
$\frac{a}{(b_{1} c_{2} - b_{2} c_{1})} = \frac{b}{(c_{1} a_{2} - a_{1} c_{2})} = \frac{- 1}{(a_{1} b_{2} - a_{2} b_{1})}$
So, from equation (1) and (2) we can write the value of $a, b$ and $c$ .
$\frac{a}{- 4 \times 4 - 1 \times 2} = \frac{b}{2 \times 1 - 5 \times 4} = \frac{- 1}{5 \times 1 - 1 \times (- 4)}$
$\frac{a}{- 16 - 2} = \frac{b}{2 - 20} = \frac{- 1}{5 + 4}$
$\frac{a}{- 18} = \frac{b}{- 18} = \frac{- 1}{9}$
$\frac{b}{- 18} = \frac{- 1}{9}$
$9 b = 18$
$b = 2$

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Q. We have two equations,

\frac{1}{5} (x - 2) = \frac{1}{4} (1 - y)

and

26 x + 3 y + 4 = 0

If we solve it using cross-multiplication, we use the following arrangement, after converting equations to the standard form

What are the values of A and B?

We have two equations,
$\frac{1}{5} (x - 2) = \frac{1}{4} (1 - y)$

and

$26 x + 3 y + 4 = 0$

If we solve it using cross-multiplication, we use the following arrangement, after converting equations to the standard form.

What are the values of A and B?

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What is the value of b for the following equation: 5a−4b=2 and a+b=4? (Use cross multiplication method)

What is the value of $b$ for the following equation: $5 a - 4 b = 2$ and $a + b = 4$ ?
(Use cross multiplication method)