1) A = 7/15 - 2/15 × 9/4
= 7/15 - 1/15 × 9/2
= 14/30 - 9/30
= 5/30
= 1/6
2) B = (25 × 10⁶ × 3 × 10⁻²) : (2 × 10²)
= (75 × 10⁴) : (2 × 10²)
= 75/2 × 10⁴⁻²
= 37,5 × 10²
= 3,75 × 10³
= 3750
3) a. C = 3√72 - 5√2
≈ 18,385
b. C = 3√72 - 5√2
= 3√(36 × 2) - 5√2
= 3 × 6√2 - 5√2
= (18 - 5)√2
= 13√2
