Question

X/y=4/9

2x+3y=40

X= ?
Y= ?

Answer 1

Explicație pas cu pas: x=4k ;y=9k ;8k+27k=40; 35k=40; k=40/35=8/7;  x=4×8/7=32/7 ;  y=9×8/7=72/7

Answer 2

Răspuns:

$\frac{x}{y} = \frac{4}{9} \\ 2x + 3y = 40 \\ 9x = 4y = > x = \frac{4y}{9} \\ 2 \times \frac{4y}{9} + 3y = 40 \\ \frac{8y}{9} + \frac{27y}{9} = \frac{360}{9} ( \times 9) \\ 35y = 360 = > y = \frac{360}{35} = \frac{72}{7} \\ x = 4 \times \frac{72}{7} \times \frac{1}{9} \\ = 4 \times \frac{8}{7} = \frac{32}{7}$