Respuesta :

a rhombus has 4 equal sides so 21 - x should equal 8x + 3

put them into a simultaneous equation and solve for x

21 - x = 8x + 3

21 - 3 = 8x + x

18 = 9x

x = 18 ÷ 9
x = 2
x is equal to 4 I think I’m not sure