Question

9b²/a-b × a²-ab/72b при a=90, b=6,4

Answer 1

$\frac{9 {b}^{2} }{a - b} \times \frac{ {a}^{2} - ab}{72b} = \frac{9 {b}^{2} }{a - b} \times \frac{a(a - b)}{8b \times 9} =b \times \frac{a}{8} = \frac{ab}{8} = \frac{90 \times 6.4}{8} = \frac{45 \times 6.4}{4} = \frac{288}{4}$