Question

plz tell me that while solving it like this where is that 10 going?​

Answer 1

12/10x=8/10{90-x}

here 10 is reduced as

transposing 10 RHS

12/10×10x=8×(90-x)

as division will change in multiplication

12x+8x=720-8x

HOPE THIS HELP YOU✌️✌️

Answer 2

let the cost price of first calculator be x

so the cost of 2nd calculator will be 900 - x

selling price of first calculator

$120\% \: of \: x = \frac{120}{100} x$

selling price of the second calculator

$80\% \: of(900 - x) = \frac{80}{100} = \frac{8}{10}(900 - x)$

since selling price of both the calculators are same

$\frac{12}{10} x = \frac{8}{10} \times (90 - x)$

12x = 7800 - 8x

(that 2 ten's zero you were asking about are added to 7800)

12x + 8x.

20x = 7200

$x = \frac{7200}{20}$

X = 360