Math question, 9th grade

Jenny spent 10.60 cents on stamps. She bought 15 more 10-cents stamps than 25-cents stamps. How many 10 cents stamps did she buy?

Hannah is 9 years old. Her mum is 39. In how many years will her mum be three times as old as Hannah?

Please don't just give me the answer but explain how did you get it, so I can do it on my own next time :) Thank you!

1st question... Is 10.60 cents a typo...? I couldn't solve it basing it on 106 cents, anyway, so I'll treat it as 1060 cents.

1) Let the no. of 25-cents stamps bought be x
The no. of 10-cents stamps bought -> x+15

25x + 10 (x+15) = 1060

25x + 10x + 150 = 1060

35x = 910

x = 26

26 + 15
= 41

She bought 41 10-cent stamps.


2) Let the number of years be x.

Hannah's age in x years = 9 + x
Her mum's age in x years = 39 + x

Since her mum will be three times as old as Hannah in x years,

3 (9 + x) = 39 + x
27 + 3x = 39 + x
2x = 12

x = 6

In 6 years time, Hannah's mum will be three times as old as her.

I hope you understand my working, and I hope it helps. :)

Let number of 10 cent stamps = X
Let number of 25 cent stamps = Y
Cost of 10 cent stamps = 10X
Cost of 25 cent stamps = 25Y

10X+25Y=1060 cents
X-Y=15

Solve the simultaneous equations :)

2. she will be 3 times as old as her mum in 6 years.
9, 27(39) 10, 30(40) 11, 33(41) 12, 36(42), 13, 39(43) 14,42(44) 15, 45(45)

after 6 years Hannah mom will be three times as old as Hannah.
as after 6 year she will be 15 and her mother will b 45....