Half a number increased by 10 is 12. Find the number.

4

Step-by-step explanation:

Equation:

1/2x + 10 = 12

Subtract 10 from both sides:

1/2x = 2

Divide by 1/2 from both sides:

x = 4

-Chetan K

9

Step-by-step explanation:

Call the Total Amount of money he had X.

Amount he used to buy pens: 3/8X

Amount of money left after buying pens: X - 3/8X = 5/8X

Amount he used to buy notebooks: 2/5 * 5/8X = 1/4X

1/4X or 2/8X for 2 notebooks, so if he spent 3/8X for notebooks, he would get 3 notebooks.

As a notebook cost 3 times a pens, so for 3/8X money, he bought 9 pens.