Представьте в виде дроби: 1) 15y^8/x^7 * x^5/24y^8 2) 18a^6b :

1) 15y^8/x^7 * x^5/24y^8 = 5/x^2 * 1/8 = 5/8x^2;

2) 18a^6b : 9a^4b/c = 18a^6b * c/9a^4b = 2a^2c;

3) 15a+6 / a-2 * a^2 + 4/25a^2 - 4 = a^2 * (15a + 6) / a - 2 + (4 * 1 - 4 * 25a^2)/25a^2 = 15a^3 + 6a^2 / a - 2 + (4 - 100a^2)/25a^2 = (25a^2 * (15a^3 + 6a^2) + (a - 2) * (4 - 100a^2)) / 25a^2 * (a - 2) = (375a^5 + 150a^4 + 4a - 8 - 100a^3 + 200a^2) / (25a^3 - 50a^2) = (375a^5 + 150a^4 - 100a^3 + 200a^2 + 4a - 8) / (25a^3 - 50a^2).

4) 7s - t/s * (s/7s-t + s/t) = 7s - t/s * s/7s-t - t/s * s/t = 7s - t/7s-t - 1 = (7s * (7s - t) - t - 1 * (7s - t))/7s-t = (49s^2 - 7st - t - 7s + t )/7s-t = (49s^2 - 7st - 7s)/7s-t.