For 10 here is the answer and for 9 i’ll reply to my comment
56/90
" / " means divide
56 divided by 90 = 0.62 with a line over the 2 because it is repeating
Let the cost price of article be x :
x + x × ( 15/100 ) = 2300
x + x × ( 5 × 3 / 5 × 20 ) = 2300
x + x × ( 3 / 20 ) = 2300
x + ( 3 × x / 20 ) = 2300
x + ( 3x / 20 ) = 2300
( 20x / 20 ) + ( 3x / 20 ) = 2300
20x + 3x / 20 = 2300
23x / 20 = 2300
Multiply both sides by 20
( 23x / 20 ) × 20 = 2300 × 20
23x = 2300 × 20
23x = 23 × 2000
Divide both sides 23
23x ÷ 23 = ( 23 × 2000 ) ÷ 23
x = Rs 2000
