There was N-amount of money, spent 40% of the amount, then spent another 30%

There was N-amount of money, spent 40% of the amount, then spent another 30%, there were 105 rubles left. How much money was there initially?

To solve the problem, you can draw up an equation, since it is known that at first you spent 40% of all money, then another 30%, and 105 rubles are left. Let’s denote by x the initial amount of money:
0.4x + (x – 0.4x) * 0.3 + 105 = x;
0.4x + 0.3x – 0.12x + 105 = x;
0.42x = 105;
x = 250 rubles.
Answer: the initial amount was 250 rubles.