Bonjour
1)
a. 18/30 = (6 x 3) / (6 x 5) = 3/5
b. 45/63 = (9 x 5) / (9 x 7) = 5/7
2)
a. 1/6 + 1/9 = (1 x 3) / (6 x 3) + (1 x 2) / (9 x 2) = 3/18 + 2/18 = 5/18
b. 3/10 - 1/4 = (3 x 2) / (10 x 2) - (1 x 5) / (4 x 5) = 6/20 - 5/20 = 1/20
3)
a. 3x (x + 2) - (- 3x² - 4x)
= 3x² + 6x + 3x² + 4x
= 6x² + 10x
b. 2 (3 - x + 2) - 2x (3 - 2x)
= 6 - 2x + 4 - 6x + 4x²
= 4x² - 8x + 10.
